I have ran the TRX11 since the early 90's starting with the original Zepplin model.... For mid to top end I haven't found a pipe yet that performs the way this pipe does...With my own quad with the powervalve cylinder, enlarged stinger, Dual silencer set up, and a 2001 Cr125.cdi The TRX11 makes power from bottom to top...It made the quad easier to race as you don't have to worry about keeping the motor"on the pipe"....