Exhibit 16 Letter from Former Accountants Securities and Exchange Commission 450 Fifth Street, N.W. Washington, DC 20549 Dear Sir: We have read and agree with the comments in Item 4 of Form 8-K, dated June 13, 1997, for the following: Southwest Royalties, Inc. Income Fund V Southwest Royalties, Inc. Income Fund VI Southwest Oil & Gas Income Fund VII-A, L.P. Southwest Royalties Institutional Income Fund VII-B, L.P. Southwest Oil & Gas Income Fund VIII-A, L.P. Southwest Royalties Institutional Income Fund VIII-B, L.P. Southwest Oil & Gas Income Fund IX-A, L.P Southwest Royalties Institutional Income Fund IX-B, L.P. Southwest Oil & Gas Income Fund X-A, L.P. Southwest Oil & Gas Income Fund X-B, L.P. Southwest Oil & Gas Income Fund X-C, L.P. Southwest Royalties Institutional Income Fund X-A, L.P. Southwest Royalties Institutional Income Fund X-B, L.P. Southwest Royalties Institutional Income Fund X-C, L.P. Southwest Developmental Drilling Fund 91-A, L.P. Southwest Oil & Gas Fund XI-A, L.P. Southwest Royalties Institutional Income Fund XI-A, L.P. Southwest Developmental Drilling 92-A, L.P. Southwest Royalties Institutional Income Fund XI-B, L.P. JOSEPH DECOSIMO AND COMPANY A Tennessee Registered Limited Liability Partnership Chattanooga, Tennessee June 13, 1997