The loudest bike is my guzzi stone 2003. It was a time attack event held by the shop Ritmo Rereno. The result showed a spec of brands... 1st Ducati, follows BMW, then GUZZI... I was 2nd in GUZZIs so it was a remarkable result for a "macaroni western" bike. My bike was almost stock. There were few modifies, open airbox lid, H-pipe, Agostini mufflers /buffles off (they are just to make it loud) front 7mm down, F-tire Pirelli Sportdemon 110/90-18, rear 365mm YSS RZ302 w/ preloads 30mm, R-tire Pirelli Diablo Strada 150/70-17. Enjoy the sound.