i'll tell you best thing I did was get the yosh r-77, 4-2-1, really notice a difference, seemed like a new bike. Throttle response seemed to be improved, felt like it had more power, like there wasn't any hesitation when I gave it more throttle. I have since switched to a brocks alien head, r-77 was to quiet for me but now after a 3+ hr ride I wish I still had the r-77. Its great quality and worth every penny, You'll love it.