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.

![!4.1 S/S Single CRF450R 17-20 System with Header Side Panel[]](https://boydsassets.specd.nz/uploads/2026/09/64c49142-8e4b-4b73-aada-f16fb55de6f6-jpg.webp)
![!4.1 S/S Single CRF450R 17-20 System with Header Side Panel[]](https://boydsassets.specd.nz/uploads/2026/09/bdbdf40d-6973-4cf4-839c-9444d98e2ebf-jpg.webp)
![!4.1 S/S Single CRF450R 17-20 System with Header Side Panel[]](https://boydsassets.specd.nz/uploads/2026/09/24a46290-c583-497f-9d80-6b10f7dd1320-jpg.webp)
![!4.1 S/S Single CRF450R 17-20 System with Header Side Panel[]](https://boydsassets.specd.nz/uploads/2026/09/ecbdbf0d-e558-463b-ab01-0d8f1d8aed83-jpg.webp)
![!4.1 S/S Single CRF450R 17-20 System with Header Side Panel[]](https://boydsassets.specd.nz/uploads/2026/09/00cec03d-0dca-476b-b5f5-ef1649578319-jpg.webp)




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