Unless you plan on running the stock exhaust pipe w/ a 8in Diameter (round) body muffler and a 4in. tip, I don't think you will have to worry about the Fartcan sound. The ST really sucks it up when it comes to exhuast gas flow, so I would recomend a quality straight through/perforated core design muffler(magnaflow/dynomax/eddlebrock). Unless you are going to mount the Muffler farther up the exhaust path, the Dynomax Race ovals (would be a direct-fit replacement part) are kinda raspy in the stock muffler position.
