If you're serious about getting more from your bike, the exhaust is one of the first places to look. Few bolt-on upgrades have as direct an influence on power delivery, torque characteristics, and overall rideability as a performance pipe.
FMF has been building performance exhausts since 1973, and in that time they've become one of the most trusted names in off-road racing. From two-stroke expansion chambers raced at the highest level of motocross to four-stroke silencers engineered with aerospace-grade materials, FMF's range covers almost every type of rider and every type of machine.
At Dirt Store, we now stock a range of FMF exhaust pipes and silencers to suit a variety of bikes and riding styles. Whether you're on a two-stroke looking to sharpen your powerband or a four-stroke rider after a serious performance upgrade, this guide will help you find the right pipe for your machine.
The Fat Pipe
The Fat Pipe is FMF's most popular two-stroke expansion chamber, and it's not hard to see why. Designed to broaden and smooth the power curve across the entire rev range, it delivers more bottom end, more mid, and improved over-rev compared to a stock pipe. The result is a more tractable, easier to ride powerband that doesn't sacrifice outright performance to get there.
Where the stock pipe on most two-strokes tends to hit hard in a narrow window, the Fat Pipe widens that window considerably. You get stronger roll-on power coming out of corners, a more powerful midrange, and a top end that keeps pulling rather than signing off early. For MX and faster-paced riding where you're spending most of your time in the mid-to-top of the rev range, it's the natural choice.
Built from carbon steel with a nickel-plated finish for durability, it's also FMF's most imitated two-stroke pipe, which says everything you need to know about how well it works. At Dirt Store, the Fat Pipe is available in fitments for the Yamaha YZ125, YZ250, Honda CR250, CR85, Suzuki RM250, and Kawasaki KX125. Head to the FMF section on our site to find your specific fitment.
The Gnarly Pipe
Where the Fat Pipe broadens the powerband across the whole rev range, the Gnarly takes a different approach. It's built specifically to maximise low-to-mid end power, delivering the kind of torque and grunt from the bottom of the rev range you'd more commonly associate with a four-stroke. For riders who spend their time in technical terrain, tight trails, or off-road environments where traction and control matter more than top-end speed, that distinction is significant.
The trade-off is top-end performance. The Gnarly signs off earlier than the Fat Pipe at the top of the rev range. But for enduro, woods riding, or any discipline where you're rarely pinning it in the upper gears, that's rarely a concern in practice. What you gain is a pipe that lets you ride in higher gears at lower revs, reducing the need to slip the clutch and giving you far more control over how the power gets to the ground.
The Gnarly is also built tougher than the Fat Pipe, constructed from 18-gauge carbon steel to withstand the punishment of off-road riding. At Dirt Store, the Gnarly is available in fitments for the Yamaha YZ250, Honda CR250, Suzuki RM250, and KTM 200. Check the FMF section on site to confirm your fitment.
The Factory 4.1 RCT
For four-stroke riders, the Factory 4.1 RCT is FMF's flagship silencer and one of the most technically advanced slip-on exhausts available for off-road use. Built entirely from aerospace-grade materials at FMF's facility in Southern California, it's a product that reflects over five decades of exhaust engineering.
The standout feature is FMF's Resonance Chamber Technology, or RCT. Rather than simply routing exhaust gases through a standard packing chamber, the RCT uses a series of internal chambers to refine exhaust flow and pressure throughout the rev range. The result is a silencer that meets strict FIM and AMA sound requirements without sacrificing power output. In fact, the chamber design actively enhances exhaust pressure to give measurable gains across the entire rpm range.
The Factory 4.1 RCT is also built with practicality in mind. Its shorter overall length compared to conventional silencers makes it less vulnerable to crash damage and centralises mass closer to the motor, which has a positive effect on handling. The end cap accepts interchangeable tuning tips, allowing riders to adjust power characteristics to suit their preference, and the design allows for quick and easy repacking when the time comes.
Available at Dirt Store with a carbon end cap, the Factory 4.1 RCT is the kind of upgrade that makes itself felt every time you ride. Head to the FMF section on site to check fitment for your bike.
Which Pipe is Right for You?
With three distinct products covering two different engine types, the choice comes down to two things: what you ride and how you ride it.
If you're on a two-stroke and you spend most of your time on the motocross track or at faster-paced events where mid-to-top end performance is the priority, the Fat Pipe is your pipe. If you're on a two-stroke but your riding is more enduro, trail, or technical off-road, the Gnarly is the better fit. It will transform how your bike behaves in the terrain that actually matters to you.
For four-stroke riders, the Factory 4.1 RCT is the answer. It's a premium upgrade that delivers genuine, measurable performance gains while keeping sound levels in check, making it as practical for trail days as it is for race days.
Still unsure? The fitment listings on the Dirt Store website will confirm which pipes are available for your specific bike, and if you need any further guidance, our team is always on hand to help point you in the right direction.
Ready to Upgrade?
FMF has spent over fifty years refining the science of exhaust performance, and the range available at Dirt Store reflects that. Whether you're chasing a broader powerband on your two-stroke, looking for more grunt in technical terrain, or ready to invest in a premium four-stroke upgrade, there's an FMF pipe built for what you need.
Head over to the FMF section at Dirt Store to browse the full range and find the right fitment for your bike.