i agree, mandrel would be better but maybe not fesible in stainless, i wouldn't go much over the 2.25" due to possible loss of back pressure, the cat is going to be pretty restrictive though, and of course you cant get the exhuast out but so quick due to header port sizing, all though cat back will free it up you would have to p&p head, install headers, cat, mid pipe and rear section all in relatively same diameter piping to truly free up exhaust, but for daily driving with a little sound just a rear section would do the trick