Hey guys...so I thought I was set on getting the M4 stainless steel slip on, but recently stumbled across a few threads on the Delkevic. I definitely like the price and it sounded quite nice in a few of the youtube videos I saw. Thoughts on the two? Is the M4 worth almost twice the price? Which sounds better? Is the M4 louder? The Delkevic also has a db killer I believe, does running with it out impact the fuel mixture at all? I just don't want to be running too rich or lean w/ a slip on. Thanks!