Personally the coolest sounding exhaust I have heard is the Kakimoto GT1 OZ. Awesome sound but loud as blazes. easily the loudest one on the market. Incredible though and better power than anything else I've tried. The HKS I did NOT lie the sound of. Sounds raspy and not as deep. The Blitz is very nice tone as is the Greddy which I also liked a lot. A cheap one which isn't too loud is the Apexi WS exhaust.