I ran a dump pipe downstream of my pre-muffler (got rid of the muffler) at the track and on the drive home once....and it was just too loud. A couple of friends in Carreras have run this same setup at the track, while I ran a pre-muffler with the factory muffler on my Carrera, and they do not pull away from me nor have they bested my track time
So don't waste your money and don't piss off the other drivers
