FMF Factory 4.1 RCT Exhaust System Yamaha Yfz450R / Yfz450X The FMF Factory 4.1 RCT full system, crafted in Southern California, is built from aerospace-grade materials that align with FMF's precise specifications. The patented MegaBomb header design lets exhaust gases expand, cool, and regenerate at a faster speed. This revolutionary design boosts torque, typically associated with longer headers, and amplifies the healthy over-rev of a short header. Compared to standard mufflers, this one is notably shorter, therefore, lowering its vulnerability to crash damage and accentuating the centralized mass design by pulling it nearer to the engine. The back-end cap is designed for swift and easy tuning, using a retaining ring to secure standard and optional inserts. Features: Massive power gains throughout the RPM range Huge weight savings over stock exhaust RTS (Rapid Tuning System) for quick and easy track-side tuning Removable spark arrestor included MegaBomb Header Quiet insert sold separately Meets AMA and FIM sound requirements 100 made in the USA Weight: Titanium / Titanium / Carbon end cap 5.7 lbs