FMF Racing KTM 250-450SXF 15-18 FE/XCF 16-18/ HQV FX250-450-501 16-18 SS 4.1 RCT SO w/CRBNCAPThe Factory 4. 1 RCT incorporates the latest in FMF Resonance Chamber Technology both internally and externally. In addition, we achieve a shorter overall length that is less susceptible to crash damage and complementary to our Factory Forward Engineering moving the muffler closer to the motor to centralize mass. The Factory 4. 1 RCT is constructed from only aerospace grade materials that meet our exacting specifications and is manufactured 100% at