Subject: File No. 4-497
From: William A Kellstrom
Affiliation: Audit Committee Chair, Markwest Hydrocarbon Inc.

March 29, 2005

We have been struggling hard with 404 compliance at MarkWest but the effort is well worth it. We are a small company with evolving controls and this approach helped us a great deal to identify our control problems and correct them. This requirement really got us to accomplish something that would have had to be done sooner or later.

This has been a good regulatory requirement and should help all investors feel better that public companies have the proper controls and reporting tools and can do an honest job of accurately reporting their results.

Please keep up the pressure on CEOs and CFOs to use these improved systems to accurately their results.