Full Exhaust System FMF Factory 4.1 RCT — Kawasaki KX 250, KX 250 X 2021–2024, titanium muffler, titanium header, blue (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: Kawasaki KX 250 (2021–2024); Kawasaki KX 250 X (2021–2024). Specifications — muffler material: Titanium, pipe material: Titanium, material: Carbon Fiber, Titanium, muffler finish: Blue Anodized, configuration: Single Canister. Note: does not meet the 2025 FIM sound limit — intended for practice and closed courses, not for FIM-sanctioned racing. QuietCore 94 dB insert included. Delivery 5–8 working days. SKU: 042398.