The ?? is....... will it sound better and peform better at the same time??? My FM has a BAD CIS in the morning and I hate it. But when its warm it sounds great, untill I smash it!!!!!!
Your Exhaust guy is an idiot. A straight through muffler flows infinately better than a baffled muffler. A magnaflow swap gives you 8hp and 14trq dyno proven. Flowmaster's are deeper sounding and actually sound better than magnaflow IMO but you might get 5hp 5trq with a flowmaster swap. Baffled mufflers like flowmaster are almost as restrictive as a factory muffler that is also chambered and baffled.I just went from banks to flowmaster and I was unhappy at first but I got 3.5 tips and I love it now.
I also talked to the exhaust shop guy and he said they all flow the same. Again this is just what he said. He said there is no considerable difference. Now maybe some of these guys that have done tests know more, so yeah just lettin ya know