FMF Exhaust - 41383 - Slip On Muffler - Titanium - Factory 4.1

The FMF Factory 4.1 RCT is a titanium slip-on muffler built around FMF's Resonance Chamber Technology, applied both inside and outside the canister. It's aimed at four-stroke off-road and motocross riders chasing more power and less weight than a standard exhaust, without moving to a full system.

The 4.1 RCT runs a deliberately short body, which keeps it further out of harm's way in a crash and works with FMF's Factory Forward Engineering approach — sitting the muffler closer to the motor to centralise mass and sharpen how the bike changes direction. It's made from aerospace-grade titanium to FMF's own alloy specification and manufactured at the company's Southern California factory.

Note: part number 41383 is a model-specific application. Please confirm it suits your exact make, model and year before ordering.

• Factory 4.1 RCT slip-on muffler for four-stroke machines
• FMF Resonance Chamber Technology applied internally and externally
• Aerospace-grade titanium body using FMF's proprietary alloy blend
• Shorter overall length, so it's less exposed to crash damage
• Factory Forward Engineering positions the muffler closer to the motor to centralise mass
• RTS (Rapid Tuning System)
• FMF claims power gains across the rev range and significant weight savings over standard
• Manufactured in FMF's Southern California facility

Confirm the application for your exact make, model and year before ordering or fitting — 41383 is a model-specific part.
Fit using the supplied hardware and the mounting method specified in FMF's instructions, and check that the muffler clears the subframe, shock and bodywork before riding.
Re-check clamps, springs and mounting bolts after the first heat cycle and then at regular intervals — vibration and heat cycling can loosen exhaust hardware.
Allow the muffler to cool completely before touching, cleaning or working on it.
Handle titanium with clean hands or gloves; oils and fingerprints can bake into the surface on the first hot run.
Clean with a mild detergent and a soft cloth. Avoid abrasive pads, harsh solvents and metal polishes on the canister, and never pressure-wash directly into the outlet.
Plug the exhaust outlet when washing the bike, and run the engine afterwards to clear any moisture.
Heat discolouration around the header end of the titanium is normal and is not a fault.
Keep the canister free of mud, oil and fuel residue, which bake on and are difficult to remove later.
Inspect the packing and internals for degrading sound quality or loss of performance, and service or repack in line with FMF's instructions for this model.
After a crash or heavy impact, check the canister, mount and joint for cracks or distortion before riding again.
Store the bike with the exhaust dry and, if it's off the bike, keep the muffler somewhere clean and dry where the outlet won't be knocked or crushed.