FMF Factory 4.1 RCT complete exhaust system — Husqvarna FE 501 2020–2023 and others, carbon (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: Husqvarna FE 501 (2020–2023); KTM XCF-W 500 (2020–2023). Specifications — muffler material: Aluminum, pipe material: Stainless Steel, material: Aluminum, Stainless Steel, end cap material: Carbon Fiber, muffler finish: Raw. Note: does not meet the 2025 FIM sound limit — intended for practice and closed courses, not for FIM-sanctioned racing. Delivery 5–8 working days. SKU: 045662.