I work with a lot of dealers and performance shops including the 2 most reputable v twin kawiengine builders FUNDY and FST. Both of them will tell you that the dyno often proves the Muzzy design best on the kawi v twin atv's. And particularly if you use their custom longer duration camshafts it shows up even more. Sometimes in fact over the years,I've heard that many have sold the system they already had to get a muzzy once they decide they want a bit more serious rpm camshafts from the engine. I'm putting the muzzy on mine,as I intend to do a standard bore built engine. The muzzy is not as loud as some stuff out there,usually a bit more mellow,but still considerably louder than stock I guess,especially when you get on it hard.....but a very nice sound,not a tin can type of thing. I've already ordered it.