Features: The Factory 4.1 RCT incorporates FMF's Resonance Chamber Technology™ both internally and externally. In addition, FMF achieves 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 is constructed from only aerospace grade materials that meet their exacting specifications and is manufactured 100% at their Southern California factory. Massive Power gains throughout the RPM range.. Huge weight savings. RTS (Rapid Tuning System). This is a one piece slip-on muffler and will mount to the standard or FMF header pipe. There is no separate mid-pipe..