The pipes are stock. I noticed on the forum that "Seadog" posted that he was having the same issue. I sent him a message inquiring if he found a fix. Hopefully I'll here back from him soon. I did install a belly pan on the bike. I'm wondering if i"m getting some kind of harmonic vibration from it. I may take it off and see if the noise goes away. Other than this noise and the somewhat clunky gears, I love the performance of this bike.