Just received a New Year's Eve package. Went to the Ace muffler store in National City. San Diego cooks it. Great job guys, same day install. They said it would take 30 to 45 days of normal driving to pack the core to put it in and get the resin. 0.22 inch, in my Chevy cab, using a Bluetooth stereo hands-free kit is still sufficient. If you want to be loud, take one less. If they have to add a pipe to compensate for the smaller muffler, you'll pay more for making welds and hangers wherever you go. I don't build a hot rod so this is perfect for my needs.