When you are all saying "tame" at idle, do you mean sound? Just asking because the general rule of thumb is short muffler=low end/throttle response and long muffler=top end. Can be affected by the total length of exhauset as well. I cut my F3's standard muffler down 6" and there is an obvious change in how much better throttle response has improved. I wrapped the perforated (1.5" tube I drilled a heap of holes in) tube in fibre glass cloth. The local exhaust shop is closed this time of year so when it opens I'm gonna get some perforated muffler tube and do it right. Not sure whether I'll go 1.75" or 2"?

 

i am new to cbr's and have little knowledge in this area, but can you cut down the stock pipe or not? would it cause issues with the back pressure? only reason i ask is because i dont have the money right now for an aftermarket pipe and dont like the looks of the long stock pipe.

 

Ya you can there is a picture on page 2 of this thread I think of a stock cut short. Seems like it would be difficult though because both the inlet and outlet are welded in place...no rivets like after market pipes.