I have 3 1/2" pipe coming off my fenderwell headers and then into Magnaflows and then dump out in front of the rear tires. Almost like a set of side-pipes, but tucked under the rocker panel. They are loud, but not at loud as the 3" Flowmasters I had on before. Those were just plain annoying. These have a low resonance to them. Plus when I go to the track, I just leave them on. I figure the only increase in performance would be in the weight savings.