Take the baffles out of your pipes if your still having the 4k rpm cap. My bike was running perfect, I put some baffle sin, she wouldnt go over about 4k. Idled and ran great, but when it hit 4k, it was stuck. Removed the baffles and she was back to her good ol self. I keep meaning to punch those baffles out a bit a reinstall but I havent gotten around to it yet.