Description
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 Muffler with Carbon End Cap
- Massive Power gains throughout the RPM range.
- Huge weight savings
- New RTS (Rapid Tuning System)
- FMF uses the highest quality proprietary blend of alloy grade titanium made especially to our standards.
- Can be used with FMF or Stock OEM Header
See fitments for your model specific bike

![4.1 RCT S/S CRF450R 2021-23 Slip On W/R Carbon cap [A]](https://boydsassets.specd.nz/uploads/2026/08/829ad7ba-9c76-49f9-a0ff-ddf485f02046-jpg.webp)

Reviews
There are no reviews yet.