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 Dual S/S CRF450R 2017-18 System with MBomb Header FMF []](https://boydsassets.specd.nz/uploads/2026/09/f32f694b-fba8-42e0-9a72-187d9d728c1a-jpg.webp)
![4.1 Dual S/S CRF450R 2017-18 System with MBomb Header FMF []](https://boydsassets.specd.nz/uploads/2026/09/2b57faa5-2600-4e60-974c-1646dbce6e30-jpg.webp)
![4.1 Dual S/S CRF450R 2017-18 System with MBomb Header FMF []](https://boydsassets.specd.nz/uploads/2026/09/7c63461a-e96c-4c21-9f20-dbe3e84f4d8f-jpg.webp)
![4.1 Dual S/S CRF450R 2017-18 System with MBomb Header FMF []](https://boydsassets.specd.nz/uploads/2026/09/4a0dbc72-fe67-48ca-ba60-b7ad68457bde-jpg.webp)
![4.1 Dual S/S CRF450R 2017-18 System with MBomb Header FMF []](https://boydsassets.specd.nz/uploads/2026/09/f9bb766a-cfe0-41d0-83ea-ac03711f500e-jpg.webp)




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