The FMF Factory 4.1RCT (Resonance Chamber Technology) Aluminum muffler is all new from FMF Racing and incorporates the latest in resonance chamber technology. A Patented core shape lowers sound levels while maintaining maximum power output, and the five –sided canister shape increases internal volume allowing for the use of more sound absorbing material. The new chamber design of the muffler also allowed FMF to enhance and refine exhaust pressure through a series of internal chambers while meeting FIM 2M-Max sound test as well as the AMA 94dB standards. All new incorporating the latest in Resonance Chamber Technology. Patented core shape lowers sound level while maintaining maximum power output. Patented canister shape increases internal volume for more sound absorbing material. Patented chamber design to enhance and refine exhaust pressure. Factory Forward Engineering centralizes mass and is less prone to crash damage. Tuned exhaust with optimized core specifications for each application. Innovative carbon rear end cap for simple installation of tuning tip inserts or spark arrestor. Stainless Steel Megabomb header included to optimize each machines power output. Light damage to the sticker, no performance lost