got one right here. with as much porting as i did to this motor and a stinger that was .60 of the inlet pipe, you could not even get to the powerband unless you were going downhill, and when you did it felt like the motor was gonna zoom off the frame and down the road. i tried a few different combinations with the stinger and found that the outlet size being the same as the inlet gave this motor such a broad powerband and made the bike so rideable, that there is no other option for me. every inch of stinger that i cut off made it better and better. maybe it only works on high rpm motors, cause thats all i've tried it on. maybe you should try it before you bash it, cause 39-40mph with a 36t sprocket and a 24.5" tire seems pretty good to me.