F.A.S.T. Class is restricted to 2 1/2in exhaust. Several of those cars are in the 9's at well over 130mph. I doubt you'd feel any difference between 2.5 and 3 inch.
I know on my 526, there was no noticeable gain going to 3 inch.
However, going from a 850 and an rpm intake, to a M1 and a "1000" cfm carb, picked up A LOT.
Every combination is different. 3 inch WILL make it louder.
Is there a point where you "need" a 3" exhaust? Like, say 600 HP - up? Would a 2.5" exhaust be enough to support that kind of power?
