The Factory 4.1 RCT incorporates FMF Resonance Chamber Technology both internally and externally In addition, achieves a shorter overall length that is less susceptible to crash damage and complementary to 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 exacting specifications and is manufactured 100% at the Southern California factory Spark arrestor and quiet insert (94dB) included - Honda CRF250R (2025); Honda CRF450RX (2025)