Originally posted by hbrwhammer
I was just wondering if a 3" exhaust was ok for a NA engine, some people have told me that it would decrease the backpressure a whole lot and in turn decrease the torque
Way too big.
2.25" or 60mm is just fine for a car with bolt-ons (intake, header, intake manifold, TB, etc)
2.5" for cars that'll be getting aggressive cams.