The 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 our southern california factory.