Thinking about getting a flowmaster exhaust system, from collectors back. I'm wondering what kind of 'fabrication' I can expect to do to get the kit to match up to headers. I have an old set of Blackjack headers (I think Hedman bought them at one time or another) that I installed in the late '80's, not sure what I will go back with after I get a new engine. Will it be close enough that I can piece together some pipe sections so I can drive it somewhere to get welded up? Or will it require heavy modifying of the h-pipe? Second question, is the 2-1/2" system adequate for a moderately built 331?