Common use of Capitalization and Valid Issuance of Purchased Units Clause in Contracts

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Date, the issued and outstanding limited partner interests of MarkWest consist of 3,997,502 Common Units and 3,000,000 Subordinated Units. The only issued and outstanding general partner interests of MarkWest are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units and Subordinated Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) (the “Form 8-A”)). (b) Other than MarkWest’s Long-Term Investment Plan and MarkWest’s other equity compensation plans, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible securities, agreements, claims or commitments of any character obligating MarkWest or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements (i) All of the issued and outstanding equity interests of each of MarkWest’s Subsidiaries are owned, directly or indirectly, by MarkWest free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilities), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWest’s Subsidiaries, as applicable) and non-assessable (except as nonassessability may be affected by Section 6.07 of the Texas Revised Uniform Limited Partnership Act, Section 18-607 of the Delaware Limited Liability Company Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) as of the Commitment Date, neither MarkWest nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, will be duly authorized by the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-A) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaser. (e) The Common Units are listed on the American Stock Exchange. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) On the applicable Closing Date, the Purchased Units shall have those rights, preferences, privileges and restrictions governing the Purchased Units as set forth in the Fourth Amended and Restated Agreement of Limited Partnership. (b) The General Partner is the sole general partner of the Partnership, with a 2.0% general partner interest in the Partnership (not including any Series A Preferred Units or Series B Preferred Units); such general partner interest is the only general partner interest of the Partnership that is issued and outstanding; and such general partner interest has been duly authorized and validly issued and is owned by the General Partner free and clear of any Liens (except restrictions on transferability contained in the Fourth Amended and Restated Agreement of Limited Partnership). (c) As of the Commitment Datedate of this Agreement, and excluding the issuance and sale of the Purchased Units as contemplated hereby, the issued and outstanding limited partner interests of MarkWest the Partnership consist of 3,997,502 92,413,598 Common Units and 3,000,000 Subordinated Units. The only issued and outstanding general partner interests of MarkWest are the interests , 6,000,000 of the General Partner described Partnership’s 7.25% Series A Cumulative Redeemable Preferred Units (“Series A Preferred Units”), 5,000,000 of the Partnership’s 8.50% Series B Cumulative Redeemable Preferred Units (“Series B Preferred Units”) and the Incentive Distribution Rights (as defined in the Partnership Agreement). All outstanding Common Units, Series A Preferred Units, Series B Preferred Units and Subordinated Units and Incentive Distribution Rights and, as applicable, the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under Sections 30, 41, 51 and 60 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) (the “Form 8-A”)). (b) Other than MarkWest’s Long-Term Investment Plan Xxxxxxxx Islands LP Act and MarkWest’s other equity compensation plans, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible securities, agreements, claims or commitments of any character obligating MarkWest or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements (i) All of the issued and outstanding equity interests of each of MarkWest’s Subsidiaries are owned, directly or indirectly, by MarkWest free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilities), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWest’s Subsidiaries, as applicable) and non-assessable (except as nonassessability may be affected by Section 6.07 of the Texas Revised Uniform Limited Partnership Act, Section 18-607 of the Delaware Limited Liability Company Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) as of the Commitment Date, neither MarkWest nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Purchased Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, thereby will be duly authorized by the Partnership pursuant to Fourth Amended and Restated Agreement (as amended as contemplated by this Agreement) of Limited Partnership, prior to the Closing Initial Closing, and, when issued and delivered to the Purchasers against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership AgreementFourth Amended and Restated Agreement of Limited Partnership) and nonassessable (except as such nonassessability may be affected by matters described under Sections 30, 41, 51 and 60 of the caption “The Partnership Agreement—Xxxxxxxx Islands LP Act and the Fourth Amended and Restated Agreement of Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-APartnership) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Fourth Amended and Restated Agreement of Limited Partnership, or this Agreement and under applicable state and federal securities laws and other than laws, (ii) such Liens as are created by the PurchaserPurchasers and (iii) such Liens as arise under the Fourth Amended and Restated Agreement of Limited Partnership, or the Xxxxxxxx Islands LP Act. Except as disclosed in the Partnership SEC Documents, there are no persons entitled to statutory, preemptive or other similar contractual rights to subscribe for the Purchased Units; and, except for the Purchased Units to be issued pursuant to this Agreement or as disclosed in the Partnership SEC Documents, no options, warrants or other rights to purchase, agreements or other obligations to issue, or rights to convert any obligations into or exchange any securities for, partnership securities or ownership interests in the Partnership are outstanding. (e) Upon issuance upon conversion of the Conversion Units in accordance with the terms of the Series C Preferred Units and the Fourth Amended and Restated Agreement of Limited Partnership, the Conversion Units will be duly authorized, validly issued, fully paid (to the extent required by the Fourth Amended and Restated Agreement of Limited Partnership) and nonassessable (except as such nonassessability may be affected by Sections 30, 41, 51 and 60 of the Xxxxxxxx Islands LP Act and the Fourth Amended and Restated Agreement of Limited Partnership) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Basic Documents and under applicable state and federal securities laws, (ii) such Liens as are created by the Purchasers and (iii) such Liens as arise under the Fourth Amended and Restated Agreement of Limited Partnership or the Xxxxxxxx Islands LP Act. (f) The Common Units are listed on the American Stock Exchange. (f) Correct NYSE, and complete copies the Partnership has not received any notice of delisting. The issuance and sale of the Partnership Agreement Purchased Units and MarkWest’s certificate the offer of limited partnership are attached hereto as Exhibit B.the Conversion Units and issuance of such Conversion Units upon conversion of the Purchased Units does not contravene NYSE rules and regulations.

Capitalization and Valid Issuance of Purchased Units. (a) As After the consummation of the Commitment DateOffering and the transactions contemplated by this Agreement, the issued and outstanding limited partner interests of MarkWest consist of 3,997,502 Common Units and 3,000,000 Subordinated Units. The only issued and outstanding general partner interests of MarkWest are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units and Subordinated Units representing limited partner interests of TLP will be as described under the caption "Capitalization" in the Registration Statement. All such units and the limited partner interests represented thereby have been will be duly authorized and validly issued in accordance with the Partnership Agreement Agreement, and are will be fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters Sections 17-303 and 17-607 of the Delaware Revised Uniform Limited Partnership Act (the "Delaware LP Act") and as otherwise described in the Registration Statement under the caption “"The Partnership Agreementpartnership agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) (the “Form 8-A”)liability"). (b) Other than MarkWest’s Long-Term Investment Plan and MarkWest’s other equity compensation plans, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior After giving effect to the Commitment Date, for Offering and the period ended December 31, 2003, MarkWest has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest unitholders may vote are issued or outstanding. Except as set forth in the first sentence of transactions contemplated by this Section 3.02(b) or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible securities, agreements, claims or commitments of any character obligating MarkWest or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements (i) All of the issued and outstanding equity interests of each of MarkWest’s Subsidiaries are ownedTLP will, directly or indirectly, by MarkWest own 100% of the outstanding limited liability company interests or partnership interests, as the case may be, in its Subsidiaries free and clear of any all Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s TLP's or MarkWest’s TLP's Subsidiaries’ ' credit facilities). Such limited liability company interests or, in the case of a TLP Entity that is a limited partnership, the limited partner interests therein, as the case may be, will be duly authorized and validly issued in accordance with the limited liability company or limited partnership agreements, as the case may be, of the respective TLP Entities, and all such ownership interests have been duly authorized, validly issued and are will be fully paid (to the extent required in under the organizational documents of MarkWest’s Subsidiaries, as applicableapplicable limited liability company agreement or limited partnership agreement) and non-assessable nonassessable (except as such nonassessability may be affected by Section 6.07 of the Texas Revised Uniform Limited Partnership Act, Section 18-607 of the Delaware Limited Liability Company Act (the "Delaware LLC Act"), Section in the case of a Delaware limited liability company, or Sections 17-303 and 17-607 of the Delaware Revised Uniform Limited Partnership ActLP Act in the case of a Delaware limited partnership). In the case of a TLP Entity that is a limited partnership, Section 450.4307 the general partner interests therein will be duly authorized and validly issued in accordance with the limited partnership agreements of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) as of the Commitment Date, neither MarkWest nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 heretosuch TLP Entity. (dc) The Common Subordinated Units being purchased by the Purchasers Purchaser hereunder and the limited partner interests represented thereby, will be duly authorized by and validly issued in accordance with the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers Purchaser against payment therefor in accordance with the terms of this Agreement, will be fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by Sections 17-303 and 17-607 of the Delaware LP Act and as otherwise described in the Registration Statement under the caption "The partnership agreement—Limited liability"), and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaser. At the Closing, the Common Units issuable upon conversion of the Purchased Units, and the limited partner interests represented thereby, upon issuance in accordance with the terms of the Subordinated Units and the Partnership Agreement will be validly issuedissued in accordance with the Partnership Agreement, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters Sections 17-303 and 17-607 of the Delaware LP Act and as otherwise described in the Registration Statement under the caption “"The Partnership Agreementpartnership agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-A) liability"), and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaser. (ed) The Common Units are listed on the American New York Stock Exchange. The Common Units issuable upon conversion of the Purchased Units have, subject to issuance, been approved for listing on the New York Stock Exchange. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, prior to the issuance and sale of the Purchased Units, as contemplated hereby, the issued and outstanding limited partner interests of MarkWest ETP consist of 3,997,502 530,654,971 Common Units, 8,853,382 Class E Units, 90,706,000 Class G Units, 81,001,069 Class H Xxxxx, 000 Class I Xxxxx, 0 Class J Units, 101,525,429 Class K Units, 1,912,569 Series A Cumulative Convertible Preferred Units and 3,000,000 Subordinated Unitsthe Incentive Distribution Rights. The only issued and outstanding general partner interests of MarkWest ETP are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units, Class E Units, Class G Units, Class H Units, Class I Units, Class K Units, Series A Preferred Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (b) Other than MarkWest’s the Second Amended and Restated Energy Transfer Partners, L.P. 2008 Long-Term Investment Plan and MarkWest’s other equity compensation plansIncentive Plan, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest ETP has no equity compensation plans that contemplate the issuance of Common Units partnership interests of ETP (or securities convertible into or exchangeable for Common Unitspartnership interests of ETP). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest ETP unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) ), as contemplated by this Agreement or as are contained provided in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest ETP or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest ETP or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest ETP or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest ETP or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest ETP or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest ETP or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (i) All of the issued and outstanding equity interests of each of MarkWestETP’s Subsidiaries (except for the entities listed on Exhibit B) are owned, directly or indirectly, by MarkWest ETP free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilitiesthe ETP Credit Facility and the indentures governing senior notes of ETP), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestETP’s Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section Sections 18‑607 and 18-607 804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act”), Section 17-607 and Sections 101.114 and 101.206 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicableTexas Business Organizations Code) and free of preemptive rights, with no personal liability attaching to the ownership thereof, rights and (ii) except as of disclosed in the Commitment DateETP SEC Documents, neither MarkWest ETP nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Purchased Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, will be duly authorized by ETP pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing Closings and, when issued and delivered to the Purchasers Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than (ii) such Liens as are created by the Purchaser. (e) The Common Units are listed on the American Stock ExchangeNYSE, and ETP has not received any notice of delisting from the NYSE. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, prior to the issuance and sale of the Purchased Units, as contemplated hereby, the issued and outstanding limited partner interests of MarkWest ETP consist of 3,997,502 530,654,971 Common Units, 8,853,382 Class E Units, 90,706,000 Class G Units, 81,001,069 Class H Xxxxx, 000 Class I Xxxxx, 0 Class J Units, 101,525,429 Class K Units, 1,912,569 Series A Cumulative Convertible Preferred Units and 3,000,000 Subordinated Unitsthe Incentive Distribution Rights. The only issued and outstanding general partner interests of MarkWest ETP are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units, Class E Units, Class G Units, Class H Units, Class I Units, Class K Units, Series A Preferred Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (b) Other than MarkWest’s the Second Amended and Restated Energy Transfer Partners, L.P. 2008 Long-Term Investment Plan and MarkWest’s other equity compensation plansIncentive Plan, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest ETP has no equity compensation plans that contemplate the issuance of Common Units partnership interests of ETP (or securities convertible into or exchangeable for Common Unitspartnership interests of ETP). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest ETP unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section ‎Section 3.02(b) ), as contemplated by this Agreement or as are contained provided in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest ETP or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest ETP or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest ETP or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest ETP or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest ETP or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest ETP or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (i) All of the issued and outstanding equity interests of each of MarkWestETP’s Subsidiaries (except for the entities listed on Exhibit B) are owned, directly or indirectly, by MarkWest ETP free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilitiesthe ETP Credit Facility and the indentures governing senior notes of ETP), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestETP’s Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section Sections 18‑607 and 18-607 804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act”), Section 17-607 and Sections 101.114 and 101.206 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicableTexas Business Organizations Code) and free of preemptive rights, with no personal liability attaching to the ownership thereof, rights and (ii) except as of disclosed in the Commitment DateETP SEC Documents, neither MarkWest ETP nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Purchased Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, will be duly authorized by ETP pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing Closings and, when issued and delivered to the Purchasers Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than (ii) such Liens as are created by the Purchaser. (e) The Common Units are listed on the American Stock ExchangeNYSE, and ETP has not received any notice of delisting from the NYSE. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, prior to the issuance and sale of the Purchased Units, as contemplated hereby, the issued and outstanding limited partner interests of MarkWest Crosstex consist of 3,997,502 49,674,770 Common Units and 3,000,000 Subordinated Units. The only issued and outstanding general partner interests of MarkWest are the interests of the General Partner described incentive distribution rights (as defined in the Partnership Agreement, the “Incentive Distribution Rights”), excluding non-vested restricted units and performance units under the LTIP. All outstanding Common Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (b) Other than MarkWest’s the Crosstex GP LLC Long-Term Investment Incentive Plan and MarkWest’s other equity compensation plans(the “LTIP”), as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Crosstex has no equity compensation plans that contemplate the issuance of Common Units partnership interests of Crosstex (or securities convertible into or exchangeable for Common Unitspartnership interests of Crosstex). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest Crosstex unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section on Schedule 3.02(b) or as are contained in the Partnership Agreement), there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, rights of first refusal, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest or any of its Subsidiaries the Crosstex Entities to issue, transfer or sell any partnership interests (including the Series A Preferred Units and the Conversion Units) or other equity interest in, MarkWest Crosstex or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests interests, or rights under any Contract requiring payment based upon the value of the equity interestsof Crosstex, (ii) obligations of MarkWest Crosstex or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest Crosstex or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) proxy agreement or voting trusts or similar agreements to which MarkWest Crosstex or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest Crosstex or any of its Subsidiaries. At . (c) The General Partner is the Closingsole general partner of Crosstex with a 2% general partner interest in Crosstex; such general partner interest has been duly authorized and validly issued in accordance with the Partnership Agreement and the General Partner owns such interest free and clear of all Liens (except restrictions on transferability contained in Section 4.6 of the Partnership Agreement and other than Liens arising under the Partnership Agreement or the Delaware LP Act). (d) Schedule B hereto correctly sets forth the name of each of the Subsidiaries of Crosstex, except the jurisdiction of incorporation or formation, as described in this Section 3.02(b)applicable, there will not be any and the Persons owning the outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership equity interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements (i) Subsidiary. All of the issued and outstanding equity interests of each of MarkWestCrosstex’s Subsidiaries (except Crosstex DC Gathering Company, J.V.) are owned, directly or indirectly, by MarkWest Crosstex free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilitiesthe Crosstex Credit Facility and the Master Shelf Agreement), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestCrosstex’s Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section Sections 18-607 and 18-804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act”), Section 17-607 Sections 101.206, 153.102, 153.202 and 153.210 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 Texas Business Organizations Code and Sections 12:1327 and 12:1328 of the Michigan Louisiana Limited Liability Company Act, Section 2030 of ). Except as disclosed in the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, Crosstex SEC Documents and except as applicable) and free of preemptive rights, with no personal liability attaching may be required pursuant to the ownership thereofCrosstex DC Gathering Company, and (ii) as of the Commitment DateJ.V. joint venture agreement, neither MarkWest Crosstex nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (de) The Common Purchased Units being purchased by the Purchasers Purchaser hereunder and the limited partner interests represented thereby, thereby will be duly authorized by Crosstex pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than laws, (ii) such Liens as are created by the Purchaser. Purchaser and (eiii) The Common Units are listed on such Liens as arise under the American Stock ExchangePartnership Agreement (as amended by Amendment No. 3 to the Partnership Agreement) or the Delaware LP Act. (f) Correct Upon issuance in accordance with this Agreement and complete copies the terms of the Series A Preferred Units, the Conversion Units will be duly authorized, validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described in Sections 17-303, 17-607 and 17-804 of the Delaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Agreement or this Agreement and MarkWest’s certificate of limited partnership under applicable state and federal securities laws, (ii) such Liens as are attached hereto created by the Purchaser and (iii) such Liens as Exhibit B.arise under the Partnership Agreement (as amended by Amendment No. 3 to the Partnership Agreement) or the Delaware LP Act.

Capitalization and Valid Issuance of Purchased Units. (a) The Purchased Units shall have those rights, preferences, privileges and restrictions governing the Common Units as set forth in the Partnership Agreement. (b) As of the Commitment Datedate of this Agreement, the issued and outstanding limited partner interests of MarkWest BreitBurn consist of 3,997,502 26,038,258 Common Units and 3,000,000 Subordinated Units. The only issued and outstanding general partner interests of MarkWest BreitBurn are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units and Subordinated Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with applicable Law and the Partnership Agreement and are fully paid (to the extent required under by applicable Law and the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). All general partner interests of BreitBurn have been duly authorized and validly issued in accordance with the Partnership Agreement. (bc) Other than MarkWest’s the BreitBurn 2006 Long-Term Investment Plan Incentive Plan, the Xxxxxxxx Amended and MarkWest’s other equity compensation plansRestated Employment Agreement or the Xxxxxxxxxxx Amended and Restated Employment Agreement, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest BreitBurn has no equity compensation plans that contemplate the issuance of Common Units partnership interests of BreitBurn (or securities convertible into or exchangeable for Common Unitspartnership interests of BreitBurn). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest unitholders the Unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) or 3.2(c), as contemplated by this Agreement, as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, calls or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest BreitBurn or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest interests in BreitBurn or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest BreitBurn or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest in BreitBurn or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest BreitBurn or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest BreitBurn or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (i) All of the issued and outstanding equity interests of each of MarkWestBreitBurn’s Subsidiaries are owned, directly or indirectly, by MarkWest BreitBurn free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilities), the BreitBurn Credit Facility) and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required by applicable Law or in the organizational documents of MarkWestBreitBurn’s Subsidiaries, as applicable) and non-assessable nonassessable (except as nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Act, Section Delaware LP Act and Sections 18-607 and 18-804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act”)) and, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, rights with no personal liability attaching to the ownership thereof, ; and (ii) except as of disclosed in the Commitment DateBreitBurn SEC Documents, neither MarkWest BreitBurn nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (de) The Common offer and sale of the Purchased Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, have been, or prior to the Closing Date, will be duly authorized by BreitBurn pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers such Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by applicable law and the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement, this Agreement or the Registration Rights Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaser. (e) The Common Units are listed on the American Stock ExchangePurchasers. (f) Correct The Purchased Units will be issued in compliance with all applicable rules of The Nasdaq Global Market. Prior to the Closing Date, BreitBurn will submit to The Nasdaq Global Market a Notification Form: Listing of Additional Common Units with respect to the Purchased Units. BreitBurn’s currently outstanding Common Units are quoted on The Nasdaq Global Market and complete copies BreitBurn has not received any notice of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.delisting.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, the issued and outstanding limited partner partnership interests of MarkWest HEP consist of 3,997,502 101,568,955 Common Units and 3,000,000 Subordinated Units. The only issued and outstanding General Partner is the sole general partner interests of MarkWest are HEP, owning of record, and to our knowledge, beneficially, the interests of non-economic general partner interest in HEP; such general partner interest is duly authorized and validly issued in accordance with the Partnership Agreement; and the General Partner described owns such general partner interest free and clear of all liens, encumbrances (except restrictions on transferability that may be imposed by federal or state securities laws or as set forth in the Partnership Agreement), security interests, equities, charges or claims. All outstanding Common Units and Subordinated Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (b) Other than MarkWestHEP’s Long-Term Investment Plan and MarkWest’s other equity compensation plansIncentive Plan, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest HEP has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest HEP’s unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) ), as contemplated by this Agreement, or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible securities, agreements, claims or commitments of any character obligating MarkWest HEP or any of its the HEP Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest HEP or any of its the HEP Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, interests or (ii) obligations of MarkWest HEP or any of its the HEP Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest HEP or any of its the HEP Subsidiaries or any such securities or agreements listed in clause (i) of this sentence sentence. Neither the offering or (iii) voting trusts sale of the Purchased Units or similar agreements the registration of the Purchased Units pursuant to which MarkWest the Registration Rights Agreement, gives rise to any rights for or relating to the registration of any Common Units or other securities of HEP other than those rights granted to the General Partner or any of its Subsidiaries Affiliates (as such term is a party with respect to defined in the voting of Partnership Agreement) under the equity interests of MarkWest or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreementsPartnership Agreement. (c) (i) All Attached as Schedule 3.02 hereto is a true and complete list of each entity in which HEP has a direct or indirect majority equity or voting interest (each, a “HEP Subsidiary” and collectively, the “HEP Subsidiaries”). Except as disclosed in the HEP SEC Documents, all of the issued and outstanding equity interests of each of MarkWest’s the HEP Subsidiaries owned by HEP are owned, directly or indirectly, by MarkWest HEP free and clear of any Liens liens, encumbrances, security interests, equities, charges or claims (except for such restrictions as may exist under applicable Law and except for such Liens liens as may be imposed under MarkWestHEP’s or MarkWest’s the HEP Subsidiaries’ credit facilitiesfacilities filed as exhibits to HEP’s SEC Documents, including the Credit Agreement), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWest’s the HEP Subsidiaries, as applicable) and non-assessable (except (x) as nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section 18-607 of the Delaware Limited Liability Company Act (the “Delaware LLC Act”), Section 17-607 6.07 of the Delaware Texas Revised Uniform Limited Partnership ActAct (“TRULPA”), Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s the HEP Subsidiaries, as applicableapplicable and (y) with respect to any general partner interests) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) except as of set forth on Schedule 3.02 or disclosed in the Commitment DateHEP SEC Documents, neither MarkWest HEP nor any of its the HEP Subsidiaries owns own any shares of capital stock or other securities of, or interest in, any other Person, or is are obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Purchased Units being purchased by the Purchasers hereunder and the limited partner partnership interests represented thereby, thereby have been or will be duly authorized by HEP pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens liens, encumbrances, security interests, equities, charges or claims and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement and under applicable state and federal securities laws Laws and other than such Liens liens, encumbrances, security interests, equities, charges or claims as are created by the PurchaserPurchasers. (e) The HEP’s currently outstanding Common Units are listed on the American The New York Stock ExchangeExchange (“NYSE”). (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate hereof, the issued and outstanding limited partner interests of MarkWest consist of 3,997,502 36,500,445 Common Units and 3,000,000 Subordinated Units. The only issued and outstanding general partner interests of MarkWest are the interests of the General Partner described and as defined in the Partnership Agreement. All outstanding Common Units and Subordinated Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under the caption “The Partnership Agreement—-Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) (the “Form 8-A”)). (b) Other than MarkWest’s Long-Term Investment Incentive Plan and MarkWest’s other equity compensation plans, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, K for the period ended December 31, 20032006, MarkWest has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest unitholders may vote are is issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) or ), as are contained in the Partnership AgreementAgreement or as contemplated by the Hydrocarbon Purchase Agreement and disclosed in the joint proxy statement/prospectus that is part of the Registration Statement on Form S-4 filed with the Commission on November 11, 2007 (File No. 333-147370), there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible securities, agreements, claims or commitments of any character obligating MarkWest or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b)) and as contemplated by the Hydrocarbon Purchase Agreement, there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. Neither the offering or sale of the Purchased Units nor registration of the Purchased Units pursuant to the Registration Rights Agreement gives rise to any rights for or relating to the registration of any Common Units or other securities of MarkWest. (i) All of the issued and outstanding equity interests of each of MarkWest’s Subsidiaries are owned, directly or indirectly, by MarkWest free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilities), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWest’s Subsidiaries, as applicable) and non-assessable (except as nonassessability may be affected by Section 6.07 of the Texas Revised Uniform Limited Partnership Act, Section 18-607 of the Delaware Limited Liability Company Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) as of the Commitment Datedate hereof, neither MarkWest nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 3.02 hereto. (d) The Common Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, will be are duly authorized by the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-A) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaser. (e) The Common Units are listed on the American New York Stock Exchange. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate hereof, and prior to the issuance and sale of the Purchased Units, the issued and outstanding limited partner interests of MarkWest Crestwood consist of 3,997,502 188,016,821 Common Units and 3,000,000 Subordinated Units. The only issued and outstanding general partner interests of MarkWest are the interests of the General Partner described incentive distribution rights (as defined in the Partnership Agreement, the “Incentive Distribution Rights”). All outstanding Common Units and Subordinated Units, Incentive Distribution Rights, Class A Preferred Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) (the “Form 8-A”)Delaware LP Act). (b) Other than MarkWest’s LongThe General Partner is the sole general partner of Crestwood with a non-Term Investment Plan economic general partner interest in Crestwood; such general partner interest has been duly authorized and MarkWest’s other equity compensation plans, as described validly issued in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) or as are contained in accordance with the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible securities, agreements, claims or commitments of any character obligating MarkWest or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity Agreement and the General Partner owns such interest in, MarkWest or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements (i) All of the issued and outstanding equity interests of each of MarkWest’s Subsidiaries are owned, directly or indirectly, by MarkWest free and clear of any all Liens (except for such (A) restrictions on transferability contained in Section 4.6 of the Partnership Agreement or as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilities), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required disclosed in the organizational documents of MarkWest’s SubsidiariesCrestwood SEC Documents (B) Liens created, as applicablearising under or securing (i) and non-assessable (except as nonassessability may be affected by Section 6.07 of the Texas Revised Uniform Limited Partnership Act, Section 18-607 of the Delaware Limited Liability Company Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act Crestwood Credit Facility or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) that certain Amended and Restated Credit Agreement, dated February 2, 2011, among Crestwood Equity Partners LP, as of borrower, JPMorgan Chase Bank, N.A., as administrative agent, and the Commitment Datelenders party thereto, neither MarkWest nor any of its Subsidiaries owns any shares of capital stock as further amended from time to time and (C) other than Liens arising under the Partnership Agreement or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 heretothe Delaware LP Act). (dc) The Common Purchased Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, thereby will be duly authorized by Crestwood pursuant to the Partnership Agreement (as amended as contemplated by this Amendment No. 3 to the Partnership Agreement) prior to the Initial Closing or applicable Subsequent Closing, as the case may be, and, when issued and delivered to the Purchasers against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Agreement (as amended by Amendment No. 3 to the Partnership Agreement) or this Agreement and under applicable state and federal securities laws and other than laws, (ii) such Liens as are created by the PurchaserPurchasers and (iii) such Liens as arise under the Partnership Agreement (as amended by Amendment No. 3 to the Partnership Agreement) or the Delaware LP Act. Except as disclosed in the Crestwood SEC Documents, there are no persons entitled to statutory, preemptive or other similar contractual rights to subscribe for the Purchased Units; and, except for the Purchased Units to be issued pursuant to this Agreement or as disclosed in the Crestwood SEC Documents, no options, warrants or other rights to purchase, agreements or other obligations to issue, or rights to convert any obligations into or exchange any securities for, partnership securities or ownership interests in Crestwood are outstanding. (ed) The Common Upon issuance in accordance with this Agreement and the terms of the Class A Preferred Units, the Conversion Units will be duly authorized, validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described in Sections 17-303, 17-607 and 17-804 of the Delaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Basic Documents and under applicable state and federal securities laws, (ii) such Liens as are listed on created by the American Stock Exchange. Purchasers and (fiii) Correct and complete copies of such Liens as arise under the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto (as Exhibit B.amended by Amendment No. 3 to the Partnership Agreement) or the Delaware LP Act.

Capitalization and Valid Issuance of Purchased Units. (a) As of April 12, 2013, and prior to the Commitment Dateissuance and sale of the Purchased Units, the issued and outstanding limited partner partnership interests of MarkWest Atlas consist of 3,997,502 70,759,959 Common Units and 3,000,000 Subordinated Units(as defined in the Limited Partnership Agreement). The only issued and outstanding general partner interests of MarkWest are the interests All of the General Partner described in the Partnership Agreement. All outstanding Common Units and Subordinated Units and the limited partner interests represented thereby Incentive Distribution Rights have been duly authorized and validly issued in accordance with applicable Law and the Limited Partnership Agreement and are fully paid (to the extent required under the Limited Partnership Agreement) and nonassessable non-assessable (except as such nonassessability non-assessability may be affected by matters described under Section 17-607 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) (the “Form 8-A”)Delaware LP Act). (b) Other than MarkWestAtlas’s existing Long-Term Investment Plan Incentive Plans, and MarkWest’s other equity existing management compensation plansarrangements, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Atlas has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units). No Atlas has no outstanding indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest unitholders the holders of Common Units may vote are issued or outstandingvote. Except as set forth in the first sentence of this Section 3.02(b) or ), as contemplated by this Agreement, as are contained in the Limited Partnership Agreement, or as described in the Atlas SEC Documents, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, calls or other rights, convertible securities, agreements, claims or commitments of any character obligating MarkWest Atlas or any of its Subsidiaries to issue, transfer or sell any limited partnership interests or other equity interest in, MarkWest interests in Atlas or any of its Subsidiaries or securities convertible into or exchangeable for such limited partnership interests or other equity interests, (ii) obligations of MarkWest Atlas or any of its Subsidiaries to repurchase, redeem or otherwise acquire any limited partnership interests or other equity interests of MarkWest in Atlas or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest Atlas or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest Atlas or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (ic) All of the issued and outstanding equity interests of each of MarkWestAtlas’s Subsidiaries (other than Atlas Pipeline Mid-Continent WestTex, LLC, Atlas Pipeline Mid-Continent WestOk, LLC, Centrahoma Processing, LLC and each of their respective Subsidiaries and, as of Closing, T2 LaSalle Gathering Company LLC, T2 Eagle Ford Gathering Company LLC and T2 EF Cogeneration Holdings LLC and each of their respective Subsidiaries) are owned, directly or indirectly, by MarkWest Atlas free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWestAtlas’s or MarkWest’s its Subsidiaries’ credit facilitiesfacilities filed as exhibits to the Atlas SEC Documents), and all such ownership interests have been duly authorized, authorized and validly issued and are fully paid (to the extent required in by applicable Law and the organizational documents of MarkWestAtlas’s Subsidiaries, as applicable) and non-assessable (except as nonassessability non-assessability may be affected by Section 6.07 of the Texas Revised Uniform Limited Partnership Act, Section 18-607 of the Delaware Limited Liability Company Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company LP Act or the organizational documents of MarkWestAtlas’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) except as of disclosed in the Commitment DateAtlas SEC Documents, neither MarkWest Atlas nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common offer and sale of the Purchased Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, and the Common Units issuable upon conversion of the Purchased Units in accordance with the terms of the Class D Units as reflected in the Certificate of Designation, are or will be duly authorized by Atlas pursuant to the Limited Partnership Agreement (Agreement, as amended as contemplated by this Agreement) the Certificate of Designation, prior to the Closing and, when issued and delivered to the Purchasers against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by applicable Law and the Limited Partnership Agreement) and nonassessable non-assessable (except as such nonassessability non-assessability may be affected by matters described under Section 17-607 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Limited Partnership Agreement, the Registration Rights Agreement and under applicable state and federal securities laws Laws and other than such Liens as are created by the PurchaserPurchasers. (e) The Atlas’s currently outstanding Common Units are listed quoted on the American The New York Stock ExchangeExchange and Atlas has not received any notice of delisting. (f) Correct The Purchased Units shall have those rights, preferences, privileges and complete copies restrictions governing the Class D Units as set forth in the Limited Partnership Agreement, as amended by the Certificate of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.Designation.

Capitalization and Valid Issuance of Purchased Units. (a) The Purchased Units shall have those rights, preferences, privileges and restrictions governing the Common Units as set forth in the Partnership Agreement. (b) As of the Commitment Datedate of this Agreement, the issued and outstanding limited partner interests of MarkWest BreitBurn consist of 3,997,502 29,006,002 Common Units and 3,000,000 Subordinated Units. The only issued and outstanding general partner interests of MarkWest BreitBurn are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units and Subordinated Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with applicable Law and the Partnership Agreement and are fully paid (to the extent required under by applicable Law and the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). All general partner interests of BreitBurn have been duly authorized and validly issued in accordance with the Partnership Agreement. (bc) Other than MarkWest’s the BreitBurn 2006 Long-Term Investment Plan Incentive Plan, the Xxxxxxxx Amended and MarkWest’s other equity compensation plansRestated Employment Agreement or the Xxxxxxxxxxx Amended and Restated Employment Agreement, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest BreitBurn has no equity compensation plans that contemplate the issuance of Common Units partnership interests of BreitBurn (or securities convertible into or exchangeable for Common Unitspartnership interests of BreitBurn). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest unitholders the Unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) 3.2(c), as contemplated by this Agreement or the Hermes Contribution Agreement or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, calls or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest BreitBurn or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest interests in BreitBurn or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest BreitBurn or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest in BreitBurn or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest BreitBurn or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest BreitBurn or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (i) All of the issued and outstanding equity interests of each of MarkWestBreitBurn’s Subsidiaries are owned, directly or indirectly, by MarkWest BreitBurn free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilities), the BreitBurn Credit Facility) and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required by applicable Law or in the organizational documents of MarkWestBreitBurn’s Subsidiaries, as applicable) and non-assessable nonassessable (except as nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Act, Section Delaware LP Act and Sections 18-607 and 18-804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable”)) and free of preemptive rights, with no personal liability attaching to the ownership thereof, ; and (ii) except as of disclosed in the Commitment DateBreitBurn SEC Documents, neither MarkWest BreitBurn nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (de) The Common offer and sale of the Purchased Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, have been, or prior to the Closing Date, will be duly authorized by BreitBurn pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers such Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by applicable law and the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement, this Agreement or the Registration Rights Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaser. (e) The Common Units are listed on the American Stock ExchangePurchasers. (f) Correct The Purchased Units will be issued in compliance with all applicable rules of The Nasdaq Global Market. Prior to the Closing Date, BreitBurn will submit to The Nasdaq Global Market a Notification Form: Listing of Additional Common Units with respect to the Purchased Units. BreitBurn’s currently outstanding Common Units are quoted on The Nasdaq Global Market and complete copies BreitBurn has not received any notice of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.delisting.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate hereof, and prior to the issuance and sale of the Purchased Units,] the issued and outstanding limited partner interests of MarkWest Breitburn consist of 3,997,502 210,930,615 Common Units and 3,000,000 Subordinated 8,000,000 Series A Cumulative Redeemable Perpetual Preferred Units (the “Series A Preferred Units. The only issued and outstanding general partner interests of MarkWest are the interests of the General Partner described in the Partnership Agreement”). All outstanding Common Units and Subordinated Series A Preferred Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) (the “Form 8-A”)Delaware LP Act). (b) Other than MarkWest’s LongEach of the General Partner and Breitburn Operating GP, LLC, a Delaware limited liability company and the general partner of the Operating LP has full limited liability company power and authority to act as general partner of Breitburn and the Operating LP, respectively, in all material respects. (c) The General Partner is the sole general partner of Breitburn with a non-Term Investment Plan economic general partner interest in Breitburn; such general partner interest has been duly authorized and MarkWest’s other equity compensation plans, as described validly issued in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) or as are contained in accordance with the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible securities, agreements, claims or commitments of any character obligating MarkWest or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity Agreement and the General Partner owns such general partner interest in, MarkWest or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements (i) All of the issued and outstanding equity interests of each of MarkWest’s Subsidiaries are owned, directly or indirectly, by MarkWest free and clear of any all Liens (except for such (A) restrictions on transferability contained in Section 4.6 of the Partnership Agreement or as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilities), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required disclosed in the organizational documents of MarkWest’s SubsidiariesBreitburn SEC Documents, as applicable(B) Liens created, arising under or securing the Breitburn Credit Facility and non-assessable the Breitburn Senior Notes and (except as nonassessability may be affected by Section 6.07 of C) other than Liens arising under the Texas Revised Uniform Limited Partnership Act, Section 18-607 of Agreement or the Delaware Limited Liability Company LP Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) as of the Commitment Date, neither MarkWest nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto). (d) The Common Purchased Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, thereby will be duly authorized by Breitburn pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing Closing, as the case may be, and, when issued and delivered to the Purchasers against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than laws, (ii) such Liens as are created by the PurchaserPurchasers and (iii) such Liens as arise under the Partnership Agreement or the Delaware LP Act. Except as disclosed in the Breitburn SEC Documents, there are no persons entitled to statutory, preemptive or other similar contractual rights to subscribe for the Purchased Units; and, except for the Purchased Units to be issued pursuant to this Agreement or as disclosed in the Breitburn SEC Documents, no options, warrants or other rights to purchase, agreements or other obligations to issue, or rights to convert any obligations into or exchange any securities for, partnership securities or ownership interests in Breitburn are outstanding. (e) The Common Upon issuance in accordance with this Agreement and the terms of the Series B Preferred Units, the Conversion Units will be duly authorized, validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described in Sections 17-303, 17-607 and 17-804 of the Delaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Basic Documents and under applicable state and federal securities laws, (ii) such Liens as are listed on created by the American Stock ExchangePurchasers and (iii) such Liens as arise under the Partnership Agreement or the Delaware LP Act. (f) Correct Except as provided for in the Partnership Agreement, there are no (i) preemptive rights or other rights to subscribe for or to purchase, nor any restriction upon the voting or transfer of, any equity securities of Breitburn or (ii) outstanding options or warrants to purchase any securities of Breitburn. Except for such rights as provided in the Registration Rights Agreement by and complete copies among Breitburn Energy Partners LP, QR Holdings (QRE), LLC, QR Energy Holdings, LLC, Quantum Resources A1, LP, Quantum Resources B, LP, Quantum Resources C, LP, QAB Carried WI, LP, QAC Carried WI, LP and Black Diamond Resources, LLC, dated as of July 23, 2014, the sale of the Partnership Purchased Units as contemplated by this Agreement and MarkWest’s certificate does not give rise to any rights for or relating to the registration of limited partnership are attached hereto as Exhibit B.any Series B Preferred Units or other securities of Breitburn.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, the issued and outstanding limited partner interests of MarkWest Crosstex consist of 3,997,502 19,565,155 Common Units, 7,001,000 Subordinated Units and 3,000,000 Subordinated Unitsthe Incentive Distribution Rights, as defined in the Partnership Agreement. The only issued and outstanding general partner interests of MarkWest Crosstex are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units, Subordinated Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Section 17-607 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (b) Other than MarkWest’s the Crosstex Energy GP, LLC Long-Term Investment Plan and MarkWest’s other equity compensation plansIncentive Plan, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Crosstex has no equity compensation plans that contemplate the issuance of Common Units partnership interests of Crosstex (or securities convertible into or exchangeable for Common Unitspartnership interests of Crosstex). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest Crosstex unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest Crosstex or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest Crosstex or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest Crosstex or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest Crosstex or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest Crosstex or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest Crosstex or any of its Subsidiaries. At None of the Closingoffering or sale of the Senior Subordinated Series C Units or the registration of the Common Units underlying the Senior Subordinated Series C Units pursuant to the Registration Rights Agreement, except all as described in contemplated by this Section 3.02(b)Agreement, there will not be gives rise to any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, rights for or relating to the registration of any Common Units or other rights, convertible or exchangeable securities, agreements, claims or commitments securities of any character by which MarkWest the Partnership other than those rights granted to the General Partner or any of its Subsidiaries will be bound calling for Affiliates (as such term is defined in the purchase or issuance Partnership Agreement) under Section 7.12 of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreementsthe Partnership Agreement. (i) All of the issued and outstanding equity interests of each of MarkWestCrosstex’s Subsidiaries (except Crosstex DC Gathering Company, J.V.) are owned, directly or indirectly, by MarkWest Crosstex free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s the Crosstex Credit Facility or MarkWest’s Subsidiaries’ credit facilitiesthe Crosstex Master Shelf Agreement), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestCrosstex’s Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by matters described in Section 6.07 17-607 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section 18-607 of the Delaware Limited Liability Company Act (the “Delaware LLC Act”), Section 17-607 Article 5.09 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Texas Limited Liability Company Act, Section 2030 Sections 3.03, 5.02 and 6.07 of the Oklahoma Texas Revised Limited Partnership Act and Sections 12:1327 and 12:1328 of the Louisiana Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicableAct) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) except as of disclosed in the Commitment DateCrosstex SEC Documents, neither MarkWest Crosstex nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Senior Subordinated Series C Units being purchased by each of the Purchasers hereunder and the limited partner interests represented thereby, will be duly authorized by Crosstex pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers such Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Section 17-607 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaserlaws. (e) The Common Units are listed on the American Stock ExchangeNASDAQ and Crosstex has not received any notice of delisting. At the Closing the notification form and supporting documentation, if any, related to the Common Units to be issued on conversion of the Purchased Units will have been filed with the NASDAQ. (f) Correct The Common Units issuable upon conversion of the Senior Subordinated Series C Units and complete copies of the limited partner interests represented thereby will be duly authorized by Crosstex pursuant to the Partnership Agreement prior to the Closing and, upon issuance in accordance with the terms of Senior Subordinated Series C Units and MarkWest’s certificate the Partnership Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described in Section 17-607 of limited partnership are attached hereto as Exhibit B.the Delaware LP Act) and will be free of any and all Liens (other than Liens created by a Purchaser with respect to Senior Subordinated Series C Units) and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, the issued and outstanding limited partner interests of MarkWest Pacific consist of 3,997,502 19,300,181 Common Units and 3,000,000 10,465,000 Subordinated UnitsUnits and the Incentive Distribution Rights, as defined in the Partnership Agreement. The only issued and outstanding general partner interests of MarkWest Pacific are the interests of the General Partner Pacific Energy GP, LP described in the Partnership Agreement. All outstanding Common Units, Subordinated Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption Delaware Revised Uniform Limited Partnership Act (the “The Partnership Agreement—Limited Liability” Delaware LP Act”) and otherwise by matters described in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the PartnershipPacific’s Registration Statement on Form 8-A S-3 (File Registration Statement No. 001333-31239) 107609), as amended (the “Pacific Form 8-AS-3”), under the caption “Description of our Common Units—Limited Liability”). (b) Other than MarkWest’s Long-Term Investment Plan and MarkWest’s other equity compensation plans, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Pacific has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units)) other than the Amended and Restated Pacific Energy GP, LP Long-Term Incentive Plan. No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest Pacific’s unitholders may vote are issued or outstanding. Except as set forth in the first sentence of contemplated by this Section 3.02(b) or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible securities, agreements, claims or commitments of any character obligating MarkWest Pacific or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest Pacific or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, other than those of the General Partners and their Affiliates pursuant to the Partnership Agreement and those that may have been issued pursuant to the Amended and Restated Pacific Energy GP, LP Long-Term Incentive Plan, (ii) obligations of MarkWest Pacific or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest Pacific or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest Pacific or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest Pacific or any of its Subsidiaries. At Neither the Closingoffering or sale of the Purchased Units or the registration of the Purchased Units pursuant to the Registration Rights Agreement, except as described in this Section 3.02(b), there will not be gives rise to any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, rights for or other rights, convertible or exchangeable securities, agreements, claims or commitments relating to the registration of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements (i) All of the issued and outstanding equity interests of each of MarkWest’s Subsidiaries are owned, directly or indirectly, by MarkWest free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilities), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWest’s Subsidiaries, as applicable) and non-assessable (except as nonassessability may be affected by Section 6.07 of the Texas Revised Uniform Limited Partnership Act, Section 18-607 of the Delaware Limited Liability Company Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) as of the Commitment Date, neither MarkWest nor any of its Subsidiaries owns any shares of capital stock Common Units or other securities ofof Pacific, or interest in, any other Person, or is obligated than those of the General Partners and their Affiliates pursuant Section 7.12(b) to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 heretothe Partnership Agreement. (dc) The Common Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, will be duly authorized by Pacific pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than such Liens as are created by the PurchaserPurchasers. (ed) The Common Units are listed for trading on the American Stock ExchangeNYSE. Prior to the Closing, the Purchased Units will have been approved for listing on the NYSE. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate hereof, the issued and outstanding limited partner interests of MarkWest consist of 3,997,502 8,242,697 Common Units and 3,000,000 2,400,000 Subordinated Units. The only issued and outstanding general partner interests of MarkWest are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units and Subordinated Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) (the “Form 8-A”)). (b) Other than MarkWest’s Long-Term Investment Plan and MarkWest’s other equity compensation plans, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, K for the period ended December 31, 20032004, MarkWest has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest unitholders may vote are is issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible securities, agreements, claims or commitments of any character obligating MarkWest or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. Except under the Prior Registration Rights Agreements and that certain Registration Rights Agreement dated July 30, 2004 among MarkWest Energy Partners, L.P. and the purchasers party thereto, neither the offering or sale of the Purchased Units nor registration of the Purchased Units pursuant to the Registration Rights Agreement gives rise to any rights for or relating to the registration of any Common Units or other securities of MarkWest. (i) All of the issued and outstanding equity interests of each of MarkWest’s Subsidiaries are owned, directly or indirectly, by MarkWest free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilities), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWest’s Subsidiaries, as applicable) and non-assessable (except as nonassessability may be affected by Section 6.07 of the Texas Revised Uniform Limited Partnership Act, Section 18-607 of the Delaware Limited Liability Company Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) as of the Commitment Datedate hereof, neither MarkWest nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, will be are duly authorized by the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-A) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaser. (e) The Common Units are listed on the American Stock Exchange. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate hereof, the issued and outstanding limited partner interests of MarkWest consist of 3,997,502 10,494,862 Common Units and 3,000,000 1,800,000 Subordinated Units. The only issued and outstanding general partner interests of MarkWest are the interests of the General Partner described and as defined in the Partnership Agreement. All outstanding Common Units and Subordinated Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) (the “Form 8-A”)). (b) Other than MarkWest’s Long-Term Investment Plan and MarkWest’s other equity compensation plans, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, K for the period ended December 31, 20032004, MarkWest has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest unitholders may vote are is issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible securities, agreements, claims or commitments of any character obligating MarkWest or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. Except under the Prior Registration Rights Agreements, and those certain Registration Rights Agreements dated July 30, 2004 and November 9, 2005, respectively, among MarkWest and the purchasers party thereto, neither the offering or sale of the Purchased Units nor registration of the Purchased Units pursuant to the Registration Rights Agreement gives rise to any rights for or relating to the registration of any Common Units or other securities of MarkWest. (i) All of the issued and outstanding equity interests of each of MarkWest’s Subsidiaries are owned, directly or indirectly, by MarkWest free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilities), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWest’s Subsidiaries, as applicable) and non-assessable (except as nonassessability may be affected by Section 6.07 of the Texas Revised Uniform Limited Partnership Act, Section 18-607 of the Delaware Limited Liability Company Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) as of the Commitment Datedate hereof, neither MarkWest nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, will be are duly authorized by the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-A) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaser. (e) The Common Units are listed on the American Stock Exchange. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) A true and correct copy of the Partnership Agreement, and each amendment thereto through the date hereof, has been filed by Crosstex with the Commission as Exhibit 3.1 to Crosstex’s Current Reports on Form 8-K (File No. 000-50067) filed on March 27, 2007, December 21, 2007, March 28, 2008, January 22, 2010 and September 14, 2012, respectively. The Purchased Units shall have those rights, preferences, privileges and restrictions governing the Common Units as reflected in the Partnership Agreement. (b) As of the Commitment Datedate of this Agreement, prior to the issuance and sale of the Purchased Units, as contemplated hereby, the issued and outstanding limited partner interests of MarkWest Crosstex consist of 3,997,502 61,046,273 Common Units, 14,705,882 Series A Preferred Units and 3,000,000 Subordinated Unitsthe Incentive Distribution Rights (as defined in the Partnership Agreement). The only issued and outstanding general partner interests of MarkWest Crosstex are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units, Series A Preferred Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (bc) Other than MarkWest’s the Crosstex Energy GP, LLC Amended and Restated Long-Term Investment Incentive Plan, the Crosstex Energy, Inc. Amended and Restated Long-Term Incentive Plan and MarkWest’s other equity compensation plansthe Crosstex Energy, as described in MarkWest’s Annual Report on Form 10Inc. 2009 Long-KTerm Incentive Plan, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Crosstex has no equity compensation plans that contemplate the issuance of Common Units partnership interests of Crosstex (or securities convertible into or exchangeable for Common Unitspartnership interests of Crosstex). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest Crosstex unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest Crosstex or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest Crosstex or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest Crosstex or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest Crosstex or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest Crosstex or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest Crosstex or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (i) All of the issued and outstanding equity interests of each of MarkWestCrosstex’s Subsidiaries are owned, directly or indirectly, by MarkWest Crosstex free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s the Crosstex Credit Facility or MarkWestthe organizational documents of Crosstex’s Subsidiaries’ credit facilities, as applicable), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestCrosstex’s Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section Sections 18-607 and 18-804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act”), Section 17-607 Sections 153.102, 153.202 and 153.210 of the Delaware Revised Uniform Limited Partnership ActTexas Business Organizations Code, Section 450.4307 and Sections 12:1327 and 12:1328 of the Michigan Louisiana Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, rights and (ii) except as of disclosed in the Commitment DateCrosstex SEC Documents, neither MarkWest Crosstex nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (de) The Common Purchased Units being purchased by each of the Purchasers hereunder and the limited partner interests represented thereby, will be thereby have been duly authorized by Crosstex pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers such Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaserlaws. (ef) The Common Units are listed on the American Stock ExchangeNASDAQ, and Crosstex has not received any notice of delisting. A “Notification Form: Listing of Additional Shares” and supporting documentation related to the Purchased Units will be filed with the NASDAQ in accordance with its rules and procedures. (fg) Correct and complete copies Neither the filing of the Partnership Registration Statement nor the offering or sale of the Purchased Units as contemplated by this Agreement and MarkWest’s certificate gives rise to any rights for or relating to the registration of limited partnership are attached hereto any Common Units or other securities of Crosstex other than as Exhibit B.have been waived.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, prior to the issuance and sale of the Purchased Units, as contemplated hereby, the issued and outstanding limited partner interests of MarkWest Regency consist of 3,997,502 372,077,138 Common Units, 6,274,483 Class F Common Units, 1,912,569 Series A Preferred Units and 3,000,000 Subordinated Unitsthe Incentive Distribution Rights. The only issued and outstanding general partner interests of MarkWest Regency are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units, Class F Common Units, Series A Preferred Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (b) Other than MarkWest’s the Regency GP LLC Long-Term Investment Incentive Plan and MarkWest’s other equity compensation plansthe Penn Virginia Resource GP, as described in MarkWest’s Annual Report on Form 10LLC Sixth Amended and Restated Long-KTerm Incentive Plan, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Regency has no equity compensation plans that contemplate the issuance of Common Units partnership interests of Regency (or securities convertible into or exchangeable for Common Unitspartnership interests of Regency). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest Regency unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) ), as contemplated by this Agreement or as are contained provided in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest Regency or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest Regency or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements (i) All of the issued and outstanding equity interests of each of MarkWest’s Subsidiaries are owned, directly or indirectly, by MarkWest free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilities), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWest’s Subsidiaries, as applicable) and non-assessable (except as nonassessability may be affected by Section 6.07 of the Texas Revised Uniform Limited Partnership Act, Section 18-607 of the Delaware Limited Liability Company Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) as of the Commitment Date, neither MarkWest nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, will be duly authorized by the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-A) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaser. (e) The Common Units are listed on the American Stock Exchange. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.,

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, prior to the issuance and sale of the Purchased Units, as contemplated hereby, the issued and outstanding limited partner interests of MarkWest Regency consist of 3,997,502 357,613,669 Common Units, 6,274,483 Class F Common Units, 1,912,569 Series A Preferred Units and 3,000,000 Subordinated Unitsthe Incentive Distribution Rights. The only issued and outstanding general partner interests of MarkWest Regency are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units, Class F Common Units, Series A Preferred Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (b) Other than MarkWest’s the Regency GP LLC Long-Term Investment Incentive Plan and MarkWest’s other equity compensation plansthe Penn Virginia Resource GP, as described in MarkWest’s Annual Report on Form 10LLC Sixth Amended and Restated Long-KTerm Incentive Plan, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Regency has no equity compensation plans that contemplate the issuance of Common Units partnership interests of Regency (or securities convertible into or exchangeable for Common Unitspartnership interests of Regency). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest Regency unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) ), as contemplated by this Agreement or as are contained provided in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest Regency or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest Regency or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest Regency or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest Regency or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest Regency or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest Regency or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (i) All of the issued and outstanding equity interests of each of MarkWestRegency’s Subsidiaries (except for the entities listed on Exhibit C) are owned, directly or indirectly, by MarkWest Regency free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilitiesthe Regency Credit Facility and the indentures governing senior notes of Regency), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestRegency’s Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section Sections 18-607 and 18-804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act”), Section 17-607 Sections 101.114 and 101.206 of the Delaware Revised Uniform Limited Partnership Act, Texas Business Organizations Code and Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 18-2054.4(H) of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicableAct) and free of preemptive rights, with no personal liability attaching to the ownership thereof, rights and (ii) except as of disclosed in the Commitment DateRegency SEC Documents, neither MarkWest Regency nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Purchased Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, will be duly authorized by Regency pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than (ii) such Liens as are created by the Purchaser. (e) The Common Units are listed on the American Stock ExchangeNYSE, and Regency has not received any notice of delisting from the NYSE. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, prior to the issuance and sale of the Purchased Units, as contemplated hereby, the issued and outstanding limited partner interests of MarkWest SUN consist of 3,997,502 99,451,043 Common Units, 16,410,780 Class C Units and 3,000,000 Subordinated Unitsthe Incentive Distribution Rights. The only issued and outstanding general partner interests of MarkWest SUN are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units, Class C Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (b) Other than MarkWest’s the Sunoco LP 2012 Long-Term Investment Plan and MarkWest’s other equity compensation plans, as described in MarkWest’s Annual Report on Form 10-KIncentive Plan, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest SUN has no equity compensation plans that contemplate the issuance of Common Units partnership interests of SUN (or securities convertible into or exchangeable for Common Unitspartnership interests of SUN). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest SUN unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) ), as contemplated by this Agreement or as are contained provided in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest SUN or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest SUN or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest SUN or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest SUN or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest SUN or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest SUN or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (i) All of the issued and outstanding equity interests of each of MarkWestSUN’s Subsidiaries are owned, directly or indirectly, by MarkWest SUN free and clear of any Liens (except for such restrictions as may exist under applicable federal or state securities Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilitiesthe SUN Credit Facility and the indentures governing senior notes of SUN), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestSUN’s Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section Sections 18-607 and 18-804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act”), Section 17-607 and Sections 101.114 and 101.206 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicableTexas Business Organizations Code) and free of preemptive rights, with no personal liability attaching to the ownership thereof, rights and (ii) except as of disclosed in the Commitment DateSUN SEC Documents, neither MarkWest SUN nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Units being purchased None of SUN’s Subsidiaries is prohibited, directly or indirectly, under any agreement or other instrument to which it is a party or is subject, from paying any dividends to SUN, from making any other distribution on such Subsidiary’s equity securities held directly or indirectly by SUN, from repaying to SUN any loans or advances to such Subsidiary from SUN or from transferring any of such Subsidiary’s properties or assets to SUN or any other Subsidiary of SUN, except as set forth in the Purchasers hereunder SUN Credit Facility and the limited partner interests represented thereby, will be indentures governing senior notes of SUN. (e) The Purchased Units have been duly authorized by SUN pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than (ii) such Liens as are created by the Purchaser. (ef) The Common Units are listed on the American Stock ExchangeNYSE, and SUN has not received any notice of delisting from the NYSE. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, prior to the issuance and sale of the Purchased Units, as contemplated hereby, the issued and outstanding limited partner interests of MarkWest Regency consist of 3,997,502 372,077,138 Common Units, 6,274,483 Class F Common Units, 1,912,569 Series A Preferred Units and 3,000,000 Subordinated Unitsthe Incentive Distribution Rights. The only issued and outstanding general partner interests of MarkWest Regency are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units, Class F Common Units, Series A Preferred Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (b) Other than MarkWest’s the Regency GP LLC Long-Term Investment Incentive Plan and MarkWest’s other equity compensation plansthe Penn Virginia Resource GP, as described in MarkWest’s Annual Report on Form 10LLC Sixth Amended and Restated Long-KTerm Incentive Plan, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Regency has no equity compensation plans that contemplate the issuance of Common Units partnership interests of Regency (or securities convertible into or exchangeable for Common Unitspartnership interests of Regency). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest Regency unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) ), as contemplated by this Agreement or as are contained provided in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest Regency or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest Regency or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest Regency or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest Regency or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest Regency or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest Regency or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (i) All of the issued and outstanding equity interests of each of MarkWestRegency’s Subsidiaries (except for the entities listed on Exhibit C) are owned, directly or indirectly, by MarkWest Regency free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilitiesthe Regency Credit Facility and the indentures governing senior notes of Regency), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestRegency’s Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section Sections 18-607 and 18-804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act”), Section 17-607 Sections 101.114 and 101.206 of the Delaware Revised Uniform Limited Partnership Act, Texas Business Organizations Code and Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 18-2054.4(H) of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicableAct) and free of preemptive rights, with no personal liability attaching to the ownership thereof, rights and (ii) except as of disclosed in the Commitment DateRegency SEC Documents, neither MarkWest Regency nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Purchased Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, will be duly authorized by Regency pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than (ii) such Liens as are created by the Purchaser. (e) The Common Units are listed on the American Stock ExchangeNYSE, and Regency has not received any notice of delisting from the NYSE. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) The Purchased Units shall have those rights, preferences, privileges and restrictions governing the Common Units as reflected in the Partnership Agreement. (b) As of the Commitment Datedate of this Agreement, prior to the issuance and sale of the Purchased Units, as contemplated hereby, and the Common Units to be issued pursuant to the Concurrent Public Offering, the issued and outstanding limited partner interests of MarkWest Crosstex consist of 3,997,502 66,896,495 Common Units, 15,072,142 Series A Preferred Units and 3,000,000 Subordinated Unitsthe Incentive Distribution Rights (as defined in the Partnership Agreement). The only issued and outstanding general partner interests of MarkWest Crosstex are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units, Series A Preferred Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (bc) Other than MarkWest’s the Crosstex Energy GP, LLC Amended and Restated Long-Term Investment Incentive Plan, the Crosstex Energy, Inc. Amended and Restated Long-Term Incentive Plan and MarkWest’s other equity compensation plansthe Crosstex Energy, as described in MarkWest’s Annual Report on Form 10Inc. 2009 Long-KTerm Incentive Plan, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Crosstex has no equity compensation plans that contemplate the issuance of Common Units partnership interests of Crosstex (or securities convertible into or exchangeable for Common Unitspartnership interests of Crosstex). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest Crosstex unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b3.02(c) or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest Crosstex or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest Crosstex or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest Crosstex or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest Crosstex or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest Crosstex or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest Crosstex or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (i) All of the issued and outstanding equity interests of each of MarkWestCrosstex’s Subsidiaries are owned, directly or indirectly, by MarkWest Crosstex free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s the Crosstex Credit Facility or MarkWestthe organizational documents of Crosstex’s Subsidiaries’ credit facilities, as applicable), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestCrosstex’s Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section Sections 18-607 and 18-804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act”), Section 17-607 Sections 153.102, 153.202 and 153.210 of the Delaware Revised Uniform Limited Partnership ActTexas Business Organizations Code, Section 450.4307 and Sections 12:1327 and 12:1328 of the Michigan Louisiana Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, rights and (ii) except as of disclosed in the Commitment DateCrosstex SEC Documents, neither MarkWest Crosstex nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (de) The Common Purchased Units being purchased by each of the Purchasers hereunder and the limited partner interests represented thereby, will be thereby have been duly authorized by Crosstex pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers such Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaserlaws. (ef) The Common Units are listed on the American Stock ExchangeNASDAQ, and Crosstex has not received any notice of delisting. A “Notification Form: Listing of Additional Shares” and supporting documentation related to the Purchased Units will be filed with the NASDAQ in accordance with its rules and procedures. (fg) Correct and complete copies Neither the filing of the Partnership Registration Statement nor the offering or sale of the Purchased Units as contemplated by this Agreement and MarkWest’s certificate gives rise to any rights for or relating to the registration of limited partnership are attached hereto any Common Units or other securities of Crosstex other than as Exhibit B.have been waived.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, the issued and outstanding limited partner interests of MarkWest Crosstex consist of 3,997,502 8,834,312 Common Units, 9,334,000 Subordinated Units, 1,495,410 Senior Subordinated Units and 3,000,000 Subordinated Unitsthe Incentive Distribution Rights, as defined in the Partnership Agreement. The only issued and outstanding general partner interests of MarkWest Crosstex are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units, Subordinated Units, Senior Subordinated Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Section 17-607 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-A”"Delaware LP Act")). (b) Other than MarkWest’s the Crosstex Energy GP, LLC Long-Term Investment Plan and MarkWest’s other equity compensation plansIncentive Plan, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Crosstex has no equity compensation plans that contemplate the issuance of Common Units partnership interests of Crosstex (or securities convertible into or exchangeable for Common Unitspartnership interests of Crosstex). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest Crosstex unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest Crosstex or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest Crosstex or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest Crosstex or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest Crosstex or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest Crosstex or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest Crosstex or any of its Subsidiaries. At None of the Closingoffering or sale of the Senior Subordinated Series B Units or the registration of the Common Units underlying the Senior Subordinated Series B Units pursuant to the Registration Rights Agreement, except all as described in contemplated by this Section 3.02(b)Agreement, there will not be gives rise to any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, rights for or relating to the registration of any Common Units or other rights, convertible or exchangeable securities, agreements, claims or commitments securities of any character by which MarkWest the Partnership other than those rights granted to the General Partner or any of its Subsidiaries will be bound calling for Affiliates (as such term is defined in the purchase or issuance Partnership Agreement) under Section 7.12 of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreementsthe Partnership Agreement. (i) All of the issued and outstanding equity interests of each of MarkWest’s Crosstex's Subsidiaries (except Crosstex DC Gathering Company, J.V.) are owned, directly or indirectly, by MarkWest Crosstex free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s the Crosstex Credit Facility or MarkWest’s Subsidiaries’ credit facilitiesthe Crosstex Master Shelf Agreement), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWest’s Crosstex's Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by matters described in Section 6.07 17-607 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section 18-607 of the Delaware Limited Liability Company Act (the "Delaware LLC Act"), Section 17-607 Article 5.09 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Texas Limited Liability Company Act, Section 2030 Sections 3.03, 5.02 and 6.07 of the Oklahoma Texas Revised Limited Partnership Act and Sections 12:1327 and 12:1328 of the Louisiana Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicableAct) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) except as of disclosed in the Commitment DateCrosstex SEC Documents, neither MarkWest Crosstex nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Senior Subordinated Series B Units being purchased by each of the Purchasers hereunder and the limited partner interests represented thereby, will be duly authorized by Crosstex pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers such Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Section 17-607 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaserlaws. (e) The Common Units are listed on the American Stock ExchangeNASDAQ. At the Closing the notification form and supporting documentation, if any, related to the Common Units to be issued on conversion of the Purchased Units will have been filed with the NASDAQ. (f) Correct The Common Units issuable upon conversion of the Senior Subordinated Series B Units and complete copies of the limited partner interests represented thereby will be duly authorized by Crosstex pursuant to the Partnership Agreement prior to the Closing and, upon issuance in accordance with the terms of Senior Subordinated Series B Units and MarkWest’s certificate the Partnership Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described in Section 17-607 of limited partnership are attached hereto as Exhibit B.the Delaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, prior to the issuance and sale of the Purchased Units, as contemplated hereby, the issued and outstanding limited partner interests of MarkWest Regency consist of 3,997,502 81,131,978 Common Units and 3,000,000 Subordinated Unitsthe Incentive Distribution Rights (as defined in the Partnership Agreement). The number of outstanding phantom units, the maximum number of Common Units into which such phantom units could convert and a vesting schedule as to such Units are set forth on Schedule 3.02(a) hereof. The only issued and outstanding general partner interests of MarkWest Regency are the interests of held by the General Partner Partner, as described in the Partnership Agreement. All outstanding Common Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (b) Other than MarkWest’s the Regency GP LLC Long-Term Investment Incentive Plan and MarkWest’s other equity compensation plans(the “LTIP”), as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Regency has no equity compensation plans that contemplate the issuance of Common Units partnership interests of Regency (or securities convertible into or exchangeable for Common Unitspartnership interests of Regency). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest Regency unitholders may vote are issued or outstanding. No Subordinated Units (as defined in the Partnership Agreement) are issued or outstanding. Except as set forth in the first sentence of this Section on Schedule 3.02(b) or as are contained in the Partnership Agreement), there are no outstanding or authorized authorized, and with respect only to Conversion Units there will not be at the time of any such conversion, (i) options, warrants, preemptive rights, subscriptions, calls, rights of first refusal, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest Regency or any of its Subsidiaries to issue, transfer or sell any partnership interests (including the Series A Preferred Units and the Conversion Units) or other equity interest in, MarkWest Regency or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests interests, or rights under any Contract requiring payment based upon the value of the equity interestsof Regency, (ii) obligations of MarkWest Regency or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest Regency or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) proxy agreement or voting trusts or similar agreements to which MarkWest Regency or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest Regency or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (i) All of the issued and outstanding equity interests of each of MarkWestRegency’s Subsidiaries (except for Xxxxxxx Lime Gathering LLC, of which Regency owns approximately 60% of the member interests, and RIGS Haynesville Partnership Co., of which Regency owns a 38% general partner interest) are owned, directly or indirectly, by MarkWest Regency free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilitiesthe Regency Credit Facility), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestRegency’s Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section Sections 18-607 and 18-804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act, Section 17-607 ”) and Article 5.09 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Texas Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, rights and (ii) except as of disclosed in the Commitment DateRegency SEC Documents, neither MarkWest Regency nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Purchased Units being purchased by each of the Purchasers hereunder and the limited partner interests represented thereby, thereby will be duly authorized by Regency pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers such Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than (ii) such Liens as are created by the PurchaserPurchasers. (e) Upon issuance in accordance with this Agreement and the terms of the Series A Preferred Units, the Conversion Units will be duly authorized, validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described in Sections 17-303, 17-607 and 17-804 of the Delaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and (ii) such Liens as are created by the Purchasers. (f) The Common Units are listed on the American Stock Exchange. (f) Correct NASDAQ, and complete copies Regency has not received any notice of delisting. As of the Partnership Agreement date hereof, a “Notification Form: Listing of Additional Shares” and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.supporting documentation, if required, related to the Conversion Units has been filed with the NASDAQ.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, the issued and outstanding limited partner membership interests of MarkWest Copano consist of 3,997,502 7,076,192 Common Units and 3,000,000 3,519,126 Subordinated Units. The only issued and outstanding general partner interests of MarkWest are the interests All of the General Partner described in the Partnership Agreement. All outstanding Common Units and Subordinated Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with applicable Law and the Partnership Limited Liability Company Agreement and are fully paid (to the extent required under the Partnership Limited Liability Company Agreement) and nonassessable (except as such nonassessability may be affected by matters described under Section 18-607 of the caption “The Partnership Agreement—Delaware Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Liability Company Act (the “Form 8-ADelaware LLC Act”)). (b) Other than MarkWestCopano’s Long-Term Investment Plan and MarkWest’s other equity compensation plansIncentive Plan, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Copano has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest Copano’s unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) ), as contemplated by this Agreement, or as are contained in the Partnership Limited Liability Company Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible securities, agreements, claims or commitments of any character obligating MarkWest Copano or any of its Subsidiaries to issue, transfer or sell any partnership limited liability company interests or other equity interest in, MarkWest Copano or any of its Subsidiaries or securities convertible into or exchangeable for such partnership limited liability company interests or equity interests, (ii) obligations of MarkWest Copano or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership limited liability company interests or equity interests of MarkWest Copano or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest Copano or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest Copano or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (i) All of the issued and outstanding equity interests of each of MarkWestCopano’s Subsidiaries are owned, directly or indirectly, by MarkWest Copano free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWestCopano’s or MarkWestCopano’s Subsidiaries’ credit facilitiesfacilities filed as exhibits to Copano’s SEC Documents), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestCopano’s Subsidiaries, as applicable) and non-assessable (except as nonassessability may be affected by Section 6.07 of the Texas Revised Uniform Limited Partnership Act, Section 18-607 of the Delaware Limited Liability Company Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWestCopano’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) except as of disclosed in the Commitment DateCopano SEC Documents, neither MarkWest Copano nor any of its Subsidiaries owns own any shares of capital stock or other securities of, or interest in, any other Person, or is are obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Purchased Units being purchased by the Purchasers hereunder and the limited partner membership interests represented thereby, will be duly authorized by Copano pursuant to the Partnership Limited Liability Company Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by applicable Law and the Partnership Limited Liability Company Agreement) and nonassessable (except as such nonassessability may be affected by matters described under Section 18-607 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LLC Act) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Limited Liability Company Agreement and under applicable state and federal securities laws and other than such Liens as are created by the PurchaserPurchasers. (e) The Common Units issuable upon conversion of the Class B Units, and the membership interests represented thereby, upon issuance in accordance with the terms of the Class B Units as reflected in the Class B Amendment will be duly authorized by Copano pursuant to the Limited Liability Company Agreement and, subject to receipt of the required unitholder approval, will be validly issued, fully paid (to the extent required by applicable Law and the Limited Liability Company Agreement) and nonassessable (except as such nonassessability may be affected by Section 18-607 of the Delaware LLC Act) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Limited Liability Company Agreement and under applicable state and federal securities laws and other than such Liens as are listed on created by the American Stock ExchangePurchasers. (f) Correct The Purchased Common Units, and complete copies the Common Units underlying the Purchased Class B Units, have been approved for quotation on The Nasdaq National Market, subject to official notice of the Partnership Agreement and MarkWestissuance. Copano’s certificate of limited partnership currently outstanding Common Units are attached hereto as Exhibit B.quoted on The Nasdaq National Market.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, prior to the issuance and sale of the Purchased Units, as contemplated hereby, the issued and outstanding limited partner interests of MarkWest Crosstex consist of 3,997,502 41,472,820 Common Units, 3,875,340 Senior Subordinated Series D Units and 3,000,000 Subordinated Unitsthe Incentive Distribution Rights (as defined in the Partnership Agreement). The only issued and outstanding general partner interests of MarkWest Crosstex are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units, Senior Subordinated Series D Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Section 17-607 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (b) Other than MarkWest’s the Crosstex Energy GP, LLC Long-Term Investment Plan and MarkWest’s other equity compensation plansIncentive Plan, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Crosstex has no equity compensation plans that contemplate the issuance of Common Units partnership interests of Crosstex (or securities convertible into or exchangeable for Common Unitspartnership interests of Crosstex). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest Crosstex unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest Crosstex or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest Crosstex or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest Crosstex or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest Crosstex or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest Crosstex or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest Crosstex or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (i) All of the issued and outstanding equity interests of each of MarkWestCrosstex’s Subsidiaries (except Crosstex DC Gathering Company, J.V.) are owned, directly or indirectly, by MarkWest Crosstex free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s the Crosstex Credit Facility or MarkWest’s Subsidiaries’ credit facilitiesthe Crosstex Master Shelf Agreement), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestCrosstex’s Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section Sections 18-607 and 18-804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act”), Section 17-607 Article 5.09 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Texas Limited Liability Company Act, Section 2030 Sections 3.03, 5.02 and 6.07 of the Oklahoma Texas Revised Limited Partnership Act and Sections 12:1327 and 12:1328 of the Louisiana Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicableAct) and free of preemptive rights, with no personal liability attaching to the ownership thereof, rights and (ii) except as of disclosed in the Commitment DateCrosstex SEC Documents, neither MarkWest Crosstex nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Purchased Units being purchased by each of the Purchasers hereunder and the limited partner interests represented thereby, thereby will be duly authorized by Crosstex pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers such Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Section 17-607 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaserlaws. (e) The Common Units are listed on the American Stock Exchange. (f) Correct NASDAQ, and complete copies Crosstex has not received any notice of delisting. As of the Partnership Agreement date hereof, a “Notification Form: Listing of Additional Shares” and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.supporting documentation, if required, related to the Purchased Units has been filed with the NASDAQ.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, prior to the issuance and sale of the Purchased Units, as contemplated hereby, the issued and outstanding limited partner interests of MarkWest SUN consist of 3,997,502 99,451,043 Common Units, 16,410,780 Class C Units and 3,000,000 Subordinated Unitsthe Incentive Distribution Rights. The only issued and outstanding general partner interests of MarkWest SUN are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units, Class C Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (b) Other than MarkWest’s the Sunoco LP 2012 Long-Term Investment Plan and MarkWest’s other equity compensation plans, as described in MarkWest’s Annual Report on Form 10-KIncentive Plan, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest SUN has no equity compensation plans that contemplate the issuance of Common Units partnership interests of SUN (or securities convertible into or exchangeable for Common Unitspartnership interests of SUN). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest SUN unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) ), as contemplated by this Agreement or as are contained provided in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest SUN or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest SUN or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest SUN or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest SUN or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest SUN or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest SUN or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (i) All of the issued and outstanding equity interests of each of MarkWestSUN’s Subsidiaries are owned, directly or indirectly, by MarkWest SUN free and clear of any Liens (except for such restrictions as may exist under applicable federal or state securities Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilitiesthe SUN Credit Facility and the indentures governing senior notes of SUN), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestSUN’s Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section Sections 18‑607 and 18-607 804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act”), Section 17-607 and Sections 101.114 and 101.206 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicableTexas Business Organizations Code) and free of preemptive rights, with no personal liability attaching to the ownership thereof, rights and (ii) except as of disclosed in the Commitment DateSUN SEC Documents, neither MarkWest SUN nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Units being purchased None of SUN’s Subsidiaries is prohibited, directly or indirectly, under any agreement or other instrument to which it is a party or is subject, from paying any dividends to SUN, from making any other distribution on such Subsidiary’s equity securities held directly or indirectly by SUN, from repaying to SUN any loans or advances to such Subsidiary from SUN or from transferring any of such Subsidiary’s properties or assets to SUN or any other Subsidiary of SUN, except as set forth in the Purchasers hereunder SUN Credit Facility and the limited partner interests represented thereby, will be indentures governing senior notes of SUN. (e) The Purchased Units have been duly authorized by SUN pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than (ii) such Liens as are created by the Purchaser. (ef) The Common Units are listed on the American Stock ExchangeNYSE, and SUN has not received any notice of delisting from the NYSE. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, the issued and outstanding limited partner interests of MarkWest K-Sea consist of 3,997,502 4,167,250 Common Units and 3,000,000 4,165,000 Subordinated UnitsUnits and the Incentive Distribution Rights, as defined in the Partnership Agreement. The only issued and outstanding general partner interests of MarkWest K-Sea are the interests of the K-Sea General Partner L.P. described in the Partnership Agreement. All outstanding Common Units, Subordinated Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described in Sections 17-303 and 17-607 of the Delaware Revised Uniform Limited Partnership Act (the “Delaware LP Act”) and otherwise by matters described in K-Sea’s Registration Statement on Form S-3 (Registration Statement No. 333-122668), as amended (the “K-Sea Form S-3”), under the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) (the “Form 8-A”)). (b) Other than MarkWestK-Sea’s Long-Term Investment Incentive Plan and MarkWestK-Sea’s other equity compensation plansEmployee Unit Purchase Plan, as described in MarkWest’s Annual Report on Form 10K-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Sea has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest K-Sea unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) or as are contained in the Partnership Agreement, the First Amended and Restated Limited Liability Company Agreement of K-Sea General Partner GP LLC, the First Amended and Restated Agreement of Limited Partnership of K-Sea General Partner L.P. and the Amended and Restated Agreement of Limited Partnership of K-Sea Operating Partnership L.P., there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest K-Sea or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest K-Sea or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest K-Sea or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest K-Sea or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest K-Sea or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest K-Sea or any of its Subsidiaries. At Neither the Closingoffering or sale of the Purchased Units or the registration of the Common Units pursuant to the Registration Rights Agreement, except all as described in contemplated by this Section 3.02(b), there will not be Agreement gives rise to any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, rights for or relating to the registration of any Common Units or other rightssecurities of the Partnership, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for other than as provided in the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreementsK-Sea Form S-3 and the Partnership Agreement. (i) All of the issued and outstanding equity interests of each of MarkWestK-Sea’s Subsidiaries are owned, directly or indirectly, by MarkWest K-Sea free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilitiesLaw), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestK-Sea’s Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by Section 6.07 matters described in Sections 17-303 and 17-607 of the Texas Revised Uniform Limited Partnership Act, Section Delaware LP Act or Sections 18-303 and 18-607 of the Delaware Limited Liability Company Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rightsrights (other than Section 5.7 of the Amended and Restated Agreement of Limited Partnership of K-Sea Operating Partnership L.P.), with no personal liability attaching to the ownership thereof, and (ii) except as of disclosed in the Commitment DateK-Sea SEC Documents, neither MarkWest K-Sea nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Units being purchased by the Purchasers Purchaser hereunder and the limited partner interests represented thereby, will be duly authorized by K-Sea pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303 and 17-607 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaser. (e) The Common Units are listed for trading on the American Stock ExchangeNYSE. Prior to the Anniversary Date, the Purchased Units will have been approved for listing on the NYSE. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate hereof, and prior to the issuance and sale of the Purchased Units, the issued and outstanding limited partner interests of MarkWest Breitburn consist of 3,997,502 210,930,615 Common Units and 3,000,000 Subordinated 8,000,000 Series A Cumulative Redeemable Perpetual Preferred Units (the “Series A Preferred Units. The only issued and outstanding general partner interests of MarkWest are the interests of the General Partner described in the Partnership Agreement”). All outstanding Common Units and Subordinated Series A Preferred Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) (the “Form 8-A”)Delaware LP Act). (b) Other than MarkWest’s LongEach of the General Partner and Breitburn Operating GP, LLC, a Delaware limited liability company and the general partner of the Operating LP has full limited liability company power and authority to act as general partner of Breitburn and the Operating LP, respectively, in all material respects. (c) The General Partner is the sole general partner of Breitburn with a non-Term Investment Plan economic general partner interest in Breitburn; such general partner interest has been duly authorized and MarkWest’s other equity compensation plans, as described validly issued in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) or as are contained in accordance with the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible securities, agreements, claims or commitments of any character obligating MarkWest or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity Agreement and the General Partner owns such general partner interest in, MarkWest or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements (i) All of the issued and outstanding equity interests of each of MarkWest’s Subsidiaries are owned, directly or indirectly, by MarkWest free and clear of any all Liens (except for such (A) restrictions on transferability contained in Section 4.6 of the Partnership Agreement or as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilities), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required disclosed in the organizational documents of MarkWest’s SubsidiariesBreitburn SEC Documents, as applicable(B) Liens created, arising under or securing the Breitburn Credit Facility and non-assessable the Breitburn Senior Notes and (except as nonassessability may be affected by Section 6.07 of C) other than Liens arising under the Texas Revised Uniform Limited Partnership Act, Section 18-607 of Agreement or the Delaware Limited Liability Company LP Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) as of the Commitment Date, neither MarkWest nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto). (d) The Common Purchased Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, thereby will be duly authorized by Breitburn pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing Closing, as the case may be, and, when issued and delivered to the Purchasers against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than laws, (ii) such Liens as are created by the PurchaserPurchasers and (iii) such Liens as arise under the Partnership Agreement or the Delaware LP Act. Except as disclosed in the Breitburn SEC Documents, there are no persons entitled to statutory, preemptive or other similar contractual rights to subscribe for the Purchased Units; and, except for the Purchased Units to be issued pursuant to this Agreement or as disclosed in the Breitburn SEC Documents, no options, warrants or other rights to purchase, agreements or other obligations to issue, or rights to convert any obligations into or exchange any securities for, partnership securities or ownership interests in Breitburn are outstanding. (e) The Common Upon issuance in accordance with this Agreement and the terms of the Series B Preferred Units, the Conversion Units will be duly authorized, validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described in Sections 17-303, 17-607 and 17-804 of the Delaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Basic Documents and under applicable state and federal securities laws, (ii) such Liens as are listed on created by the American Stock ExchangePurchasers and (iii) such Liens as arise under the Partnership Agreement or the Delaware LP Act. (f) Correct Except as provided for in the Partnership Agreement, there are no (i) preemptive rights or other rights to subscribe for or to purchase, nor any restriction upon the voting or transfer of, any equity securities of Breitburn or (ii) outstanding options or warrants to purchase any securities of Breitburn. Except for such rights as provided in the Registration Rights Agreement by and complete copies among Breitburn Energy Partners LP, QR Holdings (QRE), LLC, QR Energy Holdings, LLC, Quantum Resources A1, LP, Quantum Resources B, LP, Quantum Resources C, LP, QAB Carried WI, LP, QAC Carried WI, LP and Black Diamond Resources, LLC, dated as of July 23, 2014, the sale of the Partnership Purchased Units as contemplated by this Agreement and MarkWest’s certificate does not give rise to any rights for or relating to the registration of limited partnership are attached hereto as Exhibit B.any Series B Preferred Units or other securities of Breitburn.

Capitalization and Valid Issuance of Purchased Units. (a) As of the Commitment Datedate of this Agreement, prior to the issuance and sale of the Purchased Units, as contemplated hereby, the issued and outstanding limited partner interests of MarkWest Regency consist of 3,997,502 357,613,669 Common Units, 6,274,483 Class F Common Units, 1,912,569 Series A Preferred Units and 3,000,000 Subordinated Unitsthe Incentive Distribution Rights. The only issued and outstanding general partner interests of MarkWest Regency are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units, Class F Common Units, Series A Preferred Units and Subordinated Units Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). (b) Other than MarkWest’s the Regency GP LLC Long-Term Investment Incentive Plan and MarkWest’s other equity compensation plansthe Penn Virginia Resource GP, as described in MarkWest’s Annual Report on Form 10LLC Sixth Amended and Restated Long-KTerm Incentive Plan, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest Regency has no equity compensation plans that contemplate the issuance of Common Units partnership interests of Regency (or securities convertible into or exchangeable for Common Unitspartnership interests of Regency). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest Regency unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) ), as contemplated by this Agreement or as are contained provided in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest Regency or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest Regency or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest Regency or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest Regency or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest Regency or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest Regency or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (c) (i) All of the issued and outstanding equity interests of each of MarkWestRegency’s Subsidiaries (except for the entities listed on Exhibit C) are owned, directly or indirectly, by MarkWest Regency free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilitiesthe Regency Credit Facility and the indentures governing senior notes of Regency), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWestRegency’s Subsidiaries, as applicable) and non-assessable (except as such nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Delaware LP Act, Section Sections 18‑607 and 18-607 804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act”), Section 17-607 Sections 101.114 and 101.206 of the Delaware Revised Uniform Limited Partnership Act, Texas Business Organizations Code and Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 18-2054.4(H) of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicableAct) and free of preemptive rights, with no personal liability attaching to the ownership thereof, rights and (ii) except as of disclosed in the Commitment DateRegency SEC Documents, neither MarkWest Regency nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (d) The Common Purchased Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, will be duly authorized by Regency pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than (i) restrictions on transfer under the Partnership Agreement or this Agreement and under applicable state and federal securities laws and other than (ii) such Liens as are created by the Purchaser. (e) The Common Units are listed on the American Stock ExchangeNYSE, and Regency has not received any notice of delisting from the NYSE. (f) Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Capitalization and Valid Issuance of Purchased Units. (a) The Purchased Units shall have those rights, preferences, privileges and restrictions governing the Common Units as set forth in the Partnership Agreement. (b) As of the Commitment Datedate of this Agreement, the issued and outstanding limited partner interests of MarkWest BreitBurn consist of 3,997,502 21,975,758 Common Units and 3,000,000 Subordinated Units. The only issued and outstanding general partner interests of MarkWest BreitBurn are the interests of the General Partner described in the Partnership Agreement. All outstanding Common Units and Subordinated Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with applicable Law and the Partnership Agreement and are fully paid (to the extent required under by applicable Law and the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under in Sections 17-303, 17-607 and 17-804 of the caption “The Delaware Revised Uniform Limited Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) Act (the “Form 8-ADelaware LP Act”)). All general partner interests of BreitBurn have been duly authorized and validly issued in accordance with the Partnership Agreement. (bc) Other than MarkWest’s the BreitBurn 2006 Long-Term Investment Plan Incentive Plan, the Xxxxxxxx Amended and MarkWest’s other equity compensation plansRestated Employment Agreement or the Breitbenbach Amended and Restated Employment Agreement, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest BreitBurn has no equity compensation plans that contemplate the issuance of Common Units partnership interests of BreitBurn (or securities convertible into or exchangeable for Common Unitspartnership interests of BreitBurn). No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest unitholders the Unitholders may vote are issued or outstanding. Except as set forth in the first sentence of this Section 3.02(b) 3.2(c), as contemplated by this Agreement or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, calls or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character obligating MarkWest BreitBurn or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest interests in BreitBurn or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of MarkWest BreitBurn or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest in BreitBurn or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest BreitBurn or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest BreitBurn or any of its Subsidiaries. At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements. (i) All of the issued and outstanding equity interests of each of MarkWestBreitBurn’s Subsidiaries are owned, directly or indirectly, by MarkWest BreitBurn free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWestBreitBurn’s or MarkWest’s Subsidiaries’ credit facilities), Credit Facility) and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required by applicable Law or in the organizational documents of MarkWestBreitBurn’s Subsidiaries, as applicable) and non-assessable nonassessable (except as nonassessability may be affected by Section 6.07 matters described in Sections 17-303, 17-607 and 17-804 of the Texas Revised Uniform Limited Partnership Act, Section Delaware LP Act and Sections 18-607 and 18-804 of the Delaware Limited Liability Company Act (the “Delaware LLC Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable”)) and free of preemptive rights, with no personal liability attaching to the ownership thereof, ; and (ii) except as of disclosed in the Commitment DateBreitBurn SEC Documents, neither MarkWest BreitBurn nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person. The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto. (de) The Common offer and sale of the Purchased Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, have been, or prior to the Closing Date, will be duly authorized by BreitBurn pursuant to the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers such Purchaser against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by applicable law and the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under Sections 17-303, 17-607 and 17-804 of the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-ADelaware LP Act) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement, this Agreement or the Registration Rights Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaser. (e) The Common Units are listed on the American Stock ExchangePurchasers. (f) Correct The Purchased Units will be issued in compliance with all applicable rules of The Nasdaq Global Market. Prior to the Closing Date, BreitBurn will submit to The Nasdaq Global Market a Notification Form: Listing of Additional Common Units with respect to the Purchased Units. BreitBurn’s currently outstanding Common Units are quoted on The Nasdaq Global Market and complete copies BreitBurn has not received any notice of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.delisting.