FMF Factory 4.1 RCT Slip-On Muffler 045628 — KTM / Husqvarna / GasGas 350-450cc 2018-2023

Product Description

The FMF Factory 4.1 RCT Slip-On Muffler is the definitive performance upgrade for your 350cc or 450cc machine. Utilizing FMF’s patented Resonance Chamber Technology (RCT), this muffler features a proprietary core shape that minimizes sound output while unlocking maximum power across the entire RPM range. It is engineered to give you the competitive edge on the track or the trail.

Built with FMF’s signature Factory Forward engineering, this system is designed to centralize mass, significantly improving your bike's handling characteristics and making the unit less susceptible to crash damage. Constructed from lightweight aluminum and finished with a premium carbon fiber end cap, it offers durability without unnecessary weight, ensuring your bike remains agile and responsive under the most demanding conditions.

Top Features: FMF Factory 4.1 RCT Slip-On

• Patented Resonance Chamber Technology (RCT) for optimized sound and power delivery
• Advanced internal chamber ducts increase volume for superior exhaust flow
• Factory Forward Engineering improves mass centralization for enhanced handling
• Carbon fiber end cap design allows for tool-free installation of spark arrestors or tuning tips
• Includes QuietCore 94 dB insert and spark arrestor for total sound compliance

Please review the detailed compatibility data below to ensure an exact fitment match for your motorcycle before finalizing your purchase.

Fitment List

Frequently Asked Questions

Q: Does this muffler work with the stock header pipe?
A: Yes, it is designed to be a direct slip-on replacement that works perfectly with either your factory OEM header or an aftermarket FMF header.

Q: Is the spark arrestor easy to remove for closed-course riding?
A: It is. The innovative end cap design allows for the removal of the spark arrestor or the installation of different tuning tips by simply unscrewing four bolts.

Expert Pro-Tip: High-performance exhausts can lean out your fuel mixture. After installing this muffler, I highly recommend checking your spark plug color or having your ECU re-mapped. Ensuring your fuel map matches the increased exhaust flow will prevent your engine from running hot and will give you the crisp, immediate throttle response you are looking for.

Recommended Pairings:
o KTM 4-Stroke Performance Upgrades
o Husqvarna 4-Stroke Performance Parts
o Gas Gas 4-Stroke Performance Parts

At Moto-House MX, we carry the best brands in motocross and off-road performance. Our team has over 40 years of experience helping riders get more out of their bikes. Every order ships fast from our Central Florida location.

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