[Boogmiseter]

When I'm riding and around 4500 - 5000 rpm I lose a little power and the bike makes a deep growl sound. Once I reach 6000 rpm's it kicks back in to normal. It usually happens in 2nd - 4th gear. Any clues??

 

[spdrkt ZX7R]

Sounds like you could use a Power Commander and a remap. Did you fit an aftermarket pipe without a PC?

 

[Boogmiseter]

Yes I did put on a hindle slip-on...but I've had it for about 8 months before I had this problem.