View Full Version : How much will a catted H-pipe help?

03-02-2005, 10:18 PM
Compared to a stock 99, how much of a difference will an aftermarket H-pipe (Mac) make added to a Flowmaster Amer. Thunder after-cat system? I need a catted h-pipe cause emissions and I don't want the bother or taking the car to have cats put back on and taken off again each year.