I'm just finishing a 32 5 window, full fendered, 383 / 700R4, and I ran 2 1/2" off the headers thru 40 series Flowmasters and into 2 1/4" tailpipes. The guy that did my exhaust is a magician and ran the tailpipes with prebends up over the rearend and into megs that end in about the center of my gas tank. Looks great! As far as quiet goes, well I don't know, but I';ve got the identical setup on my roadster and it sounds great! I used that really good insulation, like Dynomax, called B-Quiet ( but less expensive!) that comes from an outfit in Saskatchewan and it keeps it pretty quiet in there. Good luck!