Hi all, could you tell me the general amount of hp I would gain from an x pipe + catback system. Also, how much do headers help (I have a stock intake).
You probably would gain 15 horsepower by replacing all 3 components of the exhaust system on a stock, unmodified motor. Probably 12 of those 15 ponies are going to come from replacing the midpipe and catback. On an unmodified motor, headers don't produce that much of a gain.