Originally Posted By: NateDN10
Originally Posted By: TallPaul
Just checked pipe size and my 2.3 Ranger 4 banger has 2.5 inch OD pipe from the Cat back to the joint, then it goes 2 inch OD to a can that must be a resonator, then a huge muffler wrapped in heat shields. So the question is, how restrictive is that stock muffler? Typically they are plugs to make it quiet, and if I replace it with a turbo muffler that is free flowing, will I notice the increase in power?
Probably not. In most cases with mildly-tuned factory motors, aftermarket exhausts only free up a few horsepower at the engine's peak. Usually not enough to notice, unless your butt-dyno is hypersensitive or prone to the placebo effect.
Correct, and they often degrade low end torque. Witness the number of Civics with F can mufflers which bog on off the line even with lots of clutch slipping.
My favorite 4 cylinder sound is a SAAB 900 Turbo, pre 1994. Just a converter and a rear muffler, with good pipe size.