Quiet Insert FMF Factory 4.1 RCT — Yamaha YZ 250, YZ 450 F 2014 (4T)

The FMF Factory 4.1 RCT is FMF's flagship four-stroke silencer. RCT (Resonance Chamber Technology) is a patented core shape that pulls the noise down while keeping the power up — so you can ride where the decibels get measured without giving up performance. Internal ducts in the chambers increase volume and improve flow, so power rises across the whole rev range. Factory Forward Engineering centralises mass, which helps handling and reduces crash damage. The rear end cap opens with four screws — you swap a tuning insert or spark arrestor without taking the silencer off. Works with the stock header or an FMF one. Fits: Yamaha YZ 250 (2014); Yamaha YZ 450 F (2014). Delivery 5–8 working days. SKU: 040681.