Introducing the all-new RS-9 Dual. The CRF's new dual-muffler configuration gave Yoshimura the opportunity to create an entirely new muffler built specifically for the dual-muffler CRFs. Yoshimura worked with top AMA Pro riders to achieve maximum performance and mass centralization, and to optimize rider usability. They achieved all this while maintaining AMA Regulation sound levels. The RS-9's uniquely sculpted carbon fiber end-caps feature a Tunable Insert System, so you can fine-tune power delivery and decibel levels to your specifications. Parallelogram-shaped muffler. Increased muffler volume over stock system, resulting in better throttle response and improved noise cancellation. Lightweight muffler construction with carbon fiber end-cap. CNC machined muffler bracket. Reduced weight over O.E.M. system.