[moegoat]

I have a 73 Grand Am w/ 4spd, it has headers. I used the 64-72 2 1/2 Flowmaster kit. The instructions say "fits 64 to 74", not really. The 73-77 A-Body uses a center outlet muffler & a uniquely bent tail pipe to help clear the spring & axle on it's way up & over. I had very little problems with the Flowmaster system, but it is very tight going up & over the rear toward the wheel side of the car, very close to the springs on both sides. Every now & then I have heard a tinny rattle in the rear but only when I am reaming the PI$$ out of the car banging it through the gears. I have never used a PYPES system so I cannot say good or bad. I think the system cost me less than $400.00. But it is for headers & is a H pipe that is more suited for a higher RPM application. I rev my built 400 to 6500 RPM, big cam big nuts.