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

![4.1 Dual S/S CRF450R 13-16 w Carb/Cap Slip Ons FMF []](https://boydsassets.specd.nz/uploads/2026/09/c3a53d8f-0203-45c3-97e0-b6ab8d45a014-jpg.webp)
![4.1 Dual S/S CRF450R 13-16 w Carb/Cap Slip Ons FMF []](https://boydsassets.specd.nz/uploads/2026/09/6f44ba37-d831-4144-a077-5c6188d5828f-jpg.webp)
![4.1 Dual S/S CRF450R 13-16 w Carb/Cap Slip Ons FMF []](https://boydsassets.specd.nz/uploads/2026/09/1377ac11-ce57-440a-a20f-1c6dc6a3bd13-jpg.webp)
![4.1 Dual S/S CRF450R 13-16 w Carb/Cap Slip Ons FMF []](https://boydsassets.specd.nz/uploads/2026/09/d5eacc6f-92fe-4826-8614-b15d6460cc6b-jpg.webp)
![4.1 Dual S/S CRF450R 13-16 w Carb/Cap Slip Ons FMF []](https://boydsassets.specd.nz/uploads/2026/09/c8dde1ea-c459-41ce-8425-a965034a486f-jpg.webp)
![4.1 Dual S/S CRF450R 13-16 w Carb/Cap Slip Ons FMF []](https://boydsassets.specd.nz/uploads/2026/09/f97d91b3-2bb1-4e53-994e-825767b8c881-jpg.webp)
![4.1 Dual S/S CRF450R 13-16 w Carb/Cap Slip Ons FMF []](https://boydsassets.specd.nz/uploads/2026/09/663dca7e-38bd-4011-8a93-be9ccf7a5d8b-jpg.webp)




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