-"Hi-Torque" exhaust system-Heavier flywheel to help smooth out the power.-Smaller countershaft sprocket to tie the engine torque to the ground-Slower turn throttle assemble-Different combustion chamber to reduce the engine's power pulses-Heavier primary drive gear for additional smoothness - See more at: :// /content/evo-125-sport-0#sthash.ihxCE1in.dpuf