FMF Factory 4.1 RCT Muffler for 2020–2023 KTM & Husqvarna Enduro / Dualsport Models

The FMF Factory 4.1 RCT (Resonance Chamber Technology) is FMF’s premium slip-on exhaust, engineered to deliver stronger power, crisp throttle response, and reduced weight compared to stock systems. Built with a stainless steel canister and a lightweight carbon fiber end cap, the 4.1 RCT combines long-term durability with race-proven performance.

RCT technology integrates FMF’s patented resonance chamber design to reduce sound output without sacrificing power, keeping performance high and noise levels compliant. The result is a smoother power curve, improved mid-range torque, and a sharper top-end pull.

This slip-on installs easily, works with stock or FMF header systems, and is designed for riders who want reliable gains and a refined exhaust note—ideal for dual sport, adventure, enduro, and motocross applications depending on the fitment.

Features:

• Stainless steel canister for long-term durability and heat resistance

• Carbon fiber end cap for reduced weight and a clean factory look

• RCT (Resonance Chamber Technology) for increased power with controlled sound output

• Engineered for improved throttle response and broader power delivery

• Lightweight design that reduces overall exhaust mass compared to stock

• Meets or approaches sound compliance standards depending on model

• Compatible with FMF or OEM headers (varies by fitment)

• USFS-approved spark arrestor available on many applications (check individual product listings)

• Made in the USA by FMF Racing

Fitment:

• 2020–2023 – Husqvarna FE250, FE350, FE450, FE501

• 2020–2023 – KTM 350 XCF-W, 450 XCF-W, 500 XCF-W

Fitment Note:  This muffler can be used with either the Stock OEM Header or a FMF header.  

Part Number: 045647