I put a universal muffler on mine, one in , two out. It sounded like a Harley idling, but like a chainsaw driving! It was way too loud and lost alot of power. I capped the two outputs with 3/4" X 6" nipples welded flush and it cut the sound down, but doesnt soud great. I just ordered a FMF Powercore to replace it. I need to order HW TPI valves and jets now.