FACTORY 4.1 RCT: Incorporates the latest in FMF Resonance Chamber Technology both internally and externally. In addition, FMF achieve a shorter overall length that is less susceptible to crash damage and complementary to their Factory Forward Engineering: moving the muffler closer to the motor to centralize mass. The Factory 4.1 RCT silencer is constructed only from aerospace-grade materials that meet FMF's exacting specifications and is manufactured 100% at their Southern California factory. Massive Power gains throughout the RPM range Huge weight savings Rapid Tuning System (RTS) FMF uses the highest quality proprietary blend of alloy grade titanium made specifically to their standards Can be used with FMF or stock OEM header pipe/s We recommend all motorcycle parts are fitted and tested by qualified professionals. Fits: Gas-Gas EX250F 2023 MC250F 2023 GasGas MC250F 2021