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.
- Available in Natural Aluminum with Carbon Fiber End Cap
- Massive Power gains throughout the RPM range.
- Huge weight savings
- New RTS (Rapid Tuning System)
- FMF uses the highest quality proprietary blend stainless steel made to proprietary standards.
Sound levels at idle speed tested at 1' above and 1' behind each
muffler on the same 21' 500 EXCF tested back to back.
Stock muffler 82
Stock w Pro Moto end cap / ultra silent insert 85
Stock w Pro Moto end cap / silent insert 86
Stock w Pro Moto end cap 88
Graves Motorsports w db killer 85
Graves Motorsports 89
Fmf q4 84
Fmf 4.1 88
Fmf power core 88
Lexx w db killer 86
Lexx w spark arrestor insert 87
Make / Model / Year
2020+ HUSQVARNA 501 FEs, FE
2020+ KTM 500 EXC-F, XCF-W