heres a few ideas ive heard, to get a nice exhaust note drill a hole through ur exhaust pipe before the muffler, get a bit of guutar string and tack weld it thourgh the pipe, voila u have a wonderful note! another one was to stick a PC fan before the muffler and ull get a turbo whistle lol, never tried it doubt i will! i was gonna try putting a whistle (from those vortex things) in the pod filter before the AFM, lame