FMF Exhaust Manifolds

FMF Racing: Five Decades of Performance Exhaust Innovation

FMF — the Flying Machine Factory — is one of the most iconic names in off-road motorsport. Founded in 1973 by Don Emler out of a Southern California garage, the brand was born from a simple obsession: going faster and having more fun on a dirt bike. What began as a passion project quickly became a revolution. When pro rider Marty Smith took to the track aboard an FMF-equipped Honda Elsinore and won, the word was out — these hand-crafted exhausts were something special.

More than 50 years later, FMF remains a family-owned and operated business deeply rooted in the culture of motocross and off-road racing. The brand has served as the official exhaust partner of the AMA Pro Motocross Championship and the FIM MXGP World Series, cementing its reputation at the highest levels of the sport. Through all of that growth, one thing has never changed: every exhaust is still engineered and built by hand in the USA.

A Complete Exhaust Lineup Built for Riders

FMF's product range covers virtually every corner of the off-road world. At the heart of the lineup are their exhaust mufflers, which include both 2-stroke silencers and 4-stroke mufflers for dirt bikes and ATVs. Legendary models like the Powercore 4, the Q4 Spark Arrestor, and the titanium Factory 4.1 RCT — which features FMF's proprietary Resonance Chamber Technology™ — have become go-to choices for weekend warriors and factory racers alike.

For riders looking to transform their machine from the ground up, FMF offers complete exhaust system kits that pair optimized headers with matched silencers for maximum power gains across the entire RPM range. These full systems eliminate the guesswork of mixing and matching components and are dyno-tested for every specific application.

The 2-stroke faithful will find FMF's exhaust expansion pipes to be among the most celebrated in the industry. Iconic designs like the Gnarly and the Factory Fatty have been shaping 2-stroke powerbands for decades — the nickel-plated Gnarly is so widely imitated it has become the benchmark by which all other expansion chambers are judged.

On the 4-stroke side, FMF's exhaust headers — most notably the patented PowerBomb header — are engineered to increase exhaust flow by utilizing a precisely placed expansion chamber in the initial header stage, boosting performance while also helping to reduce overall sound output. These headers are available in moto and supercross-specific configurations to suit different riding demands.

Rounding out the lineup are FMF's exhaust pipes, which cover a wide variety of platforms and riding styles. Whether you're threading tight trails, launching off motocross jumps, or exploring dual-sport routes, FMF's Tru-Flo stamping process ensures every pipe delivers a precise fit and consistent, track-tested performance.

Why Riders Trust FMF

FMF's enduring reputation is built on a commitment to real-world performance. Their products are used by champions across motocross, supercross, and off-road racing, and are manufactured from premium materials including aerospace-grade titanium and aircraft-grade aluminum. From a first-time trail rider bolting on a slip-on to a factory team preparing for a championship, FMF has engineered a solution — and done so for over half a century.