Predator

I got the Imco cat back and it sounds great, then again it could be partly due to my custom x-pipe; but in general, my car is throaty in low and mean sounding in the higher revs. I heard flowmasters on other cars (not 5.0 mustangs) and I was surprisingly dissappointed with the sound. In my mind, it was just too obnoxious.

The H or X pipe will also affect the sound of your car. X is a bit more aggressive sounding at high revs, while H is throatier all around. I've also heard that the X pipe can be about 2-5 more hp, just because it naturally flows better.