FMF Exhaust System Kit

FMF Exhaust System Kits: Race-Proven Performance for Every Rider

When it comes to complete exhaust system kits for off-road and motocross machines, few names carry the weight of FMF Racing. Exhaust system kits are the cornerstone of FMF's legacy — and for good reason. These full systems pair a precisely engineered header with a matched silencer, delivering unified gains in power, sound management, and weight savings that no single component upgrade can replicate on its own.

Built From the Ground Up in Southern California

FMF, short for Flying Machine Factory, has been engineering exhaust systems since 1973. The brand is proudly made in the USA, and every exhaust kit reflects that commitment to craftsmanship. FMF's exhaust systems cover both 2-stroke and 4-stroke platforms, making them one of the most versatile choices for riders across all disciplines — motocross, enduro, supercross, and trail.

Signature Product Lines in FMF Exhaust System Kits

FMF's exhaust system kits are built around several distinct, purpose-engineered product families:

• Factory 4.1 RCT Full System: FMF's flagship 4-stroke kit. The Factory 4.1 RCT incorporates FMF's proprietary Resonance Chamber Technology™ both internally and externally for enhanced power and refined sound control. It is constructed from aerospace-grade materials and manufactured entirely at FMF's Southern California facility. The system uses a shorter overall length to centralize mass and reduce susceptibility to crash damage — a feature FMF calls Factory Forward Engineering.
• PowerCore 4 with MegaBomb Header: A potent pairing for 4-stroke riders who want race-inspired performance at a compelling value. The MegaBomb header boosts horsepower by up to 3hp while actually lowering noise levels by as much as 1.5dB. The PowerCore 4 muffler works in concert with the header to deliver improved torque across the entire power curve.
• Factory Fatty & SST Systems (2-Stroke): For two-stroke machines, FMF's complete system kits built around the Factory Fatty expansion chamber deliver broader, smoother power with stronger low-end and mid-range pull while also improving over-rev. The SST pipe, described by FMF as a blend of the Fatty and Rev pipe designs, offers an all-around power increase with additional mid and top-end without sacrificing low end.
• Mini PowerCore 4 System: Purpose-built for mini bikes, this complete kit features a Hi-Flo stainless steel core, aircraft-grade aluminum canister, and stainless steel header. It is available in standard, closed-course big bore, and spark arrestor versions for trail-legal riding.
• Gnarly Pipe Systems (2-Stroke Off-Road): The Gnarly focuses on lower RPM horsepower and torque, engineered specifically for tight terrain and aggressive off-road conditions in 200cc through 500cc machines.

What Sets FMF Exhaust System Kits Apart

FMF's exhaust system kits are handcrafted using premium materials including carbon steel, titanium, and other exclusive alloys — not mass-produced overseas. The PowerBomb and MegaBomb headers leverage FMF's patented chamber technology, strategically expanding and contracting exhaust gases at precise points in the header to increase flow by nearly 10% while simultaneously acting as a pre-muffler to manage sound output. Whether you ride a 2-stroke trail bike or a 4-stroke motocross machine, FMF offers a complete system tuned to your specific engine, platform, and riding style.