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

![I 4.1 RCT Ti Blue YZ250F 19-20 w/carb end cap Slip On []](https://boydsassets.specd.nz/uploads/2026/09/fbff3182-c1cc-4287-b59c-355ce249dad8-jpg.webp)
![I 4.1 RCT Ti Blue YZ250F 19-20 w/carb end cap Slip On []](https://boydsassets.specd.nz/uploads/2026/09/758bc899-7e2d-44f7-ae3f-ee38cb6bb5e2-jpg.webp)
![I 4.1 RCT Ti Blue YZ250F 19-20 w/carb end cap Slip On []](https://boydsassets.specd.nz/uploads/2026/09/bef4d4f0-e469-49af-94b3-e6e2e0bd235a-jpg.webp)
![I 4.1 RCT Ti Blue YZ250F 19-20 w/carb end cap Slip On []](https://boydsassets.specd.nz/uploads/2026/09/c44b54ce-6b2b-4e2e-8956-a22ebc726aea-jpg.webp)
![I 4.1 RCT Ti Blue YZ250F 19-20 w/carb end cap Slip On []](https://boydsassets.specd.nz/uploads/2026/09/0e6e9f8b-d49c-4645-a778-51bb4b126903-jpg.webp)
![I 4.1 RCT Ti Blue YZ250F 19-20 w/carb end cap Slip On []](https://boydsassets.specd.nz/uploads/2026/09/cc3cf9b1-61b0-4ebd-bb23-671ea72f6f9f-jpg.webp)
![I 4.1 RCT Ti Blue YZ250F 19-20 w/carb end cap Slip On []](https://boydsassets.specd.nz/uploads/2026/09/a88dd0aa-01a3-4d2d-ac12-2338ce3bf367-jpg.webp)




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