What muffler are you guys running? Mine is the stock one. I was told by someone to drill 2-3 3/8" holes in the baffle inside the muffler. He said to drill one at a time and recheck the rpms. With one hole I picked up 200 rpms. I drilled a second hole and it went back down to about 6000 tops with my 22x10 Zing. I notice there wasnt enough room in there to get another hole in there so I just used my Dremel to open the space between the two holes I had made thus ending up with one oblong hole. Again I had no gain in rpms ... still about 6000. So now I am getting another stock muffler to start over with. Maybe just drill one hole and leave it at that. I know they have been drilling out the stock mufflers on the 80 twin to pick up quite a bit in rpms.

Chuck