ONLY fits YZ250f 19-23 DOES NOT FIT A YZ450F Factory 4.1 RCT Slip-On FMF Racing Titanium w/ carbon fiber end cap All new incorporating the latest in Resonance Chamber Technology Patented core shape lowers sound level while maintaining maximum power output Patented canister shape increases internal volume for more sound absorbing material Patented chamber design to enhance and refine exhaust pressure Factory Forward Engineering centralizes mass and is less prone to crash damage Tuned exhaust with optimized core specifications for each application Innovative rear end cap for simple installation of tuning tip inserts or spark arrestor Titanium mid-pipe for extreme light weight