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 Dual Ti CRF250R 2018-21 w Carb/Cap Slip Ons FMF []](https://boydsassets.specd.nz/uploads/2026/09/4fd43e67-9bc4-4912-bf30-1fdb6acabfec-jpg.webp)
![I 4.1 Dual Ti CRF250R 2018-21 w Carb/Cap Slip Ons FMF []](https://boydsassets.specd.nz/uploads/2026/09/6d0d6200-f8d8-45d2-99ba-bc9014547131-jpg.webp)
![I 4.1 Dual Ti CRF250R 2018-21 w Carb/Cap Slip Ons FMF []](https://boydsassets.specd.nz/uploads/2026/09/ce748df0-36fd-4944-ba04-edd25a6057ff-jpg.webp)
![I 4.1 Dual Ti CRF250R 2018-21 w Carb/Cap Slip Ons FMF []](https://boydsassets.specd.nz/uploads/2026/09/9a4e6a66-eb0a-4f2c-84a0-b9122f9658e3-jpg.webp)
![I 4.1 Dual Ti CRF250R 2018-21 w Carb/Cap Slip Ons FMF []](https://boydsassets.specd.nz/uploads/2026/09/23a8976e-9544-4004-96fd-5091b184f1df-jpg.webp)
![I 4.1 Dual Ti CRF250R 2018-21 w Carb/Cap Slip Ons FMF []](https://boydsassets.specd.nz/uploads/2026/09/c3f0cfc5-d8ef-44a0-bda9-7cdcb4913eee-jpg.webp)
![I 4.1 Dual Ti CRF250R 2018-21 w Carb/Cap Slip Ons FMF []](https://boydsassets.specd.nz/uploads/2026/09/2a139127-c0b9-406f-b96e-25f0676be8bc-jpg.webp)




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