FMF Exhaust - 45658 - Slip On Muffler - Anodised Titanium - Factory 4.1 RCT

The FMF Factory 4.1 RCT is a slip-on muffler built around FMF's Resonance Chamber Technology, applied both internally and externally to broaden power delivery across the rev range. Its shorter canister sits closer to the engine in line with FMF's Factory Forward Engineering approach, centralising mass and leaving less muffler hanging out where it can be damaged in a crash.

Made from aerospace-grade materials and manufactured at FMF's Southern California factory, this version pairs an anodised titanium canister with a carbon fibre end cap and a stainless steel mid-pipe. It suits enduro and off-road riders on the Sherco four-stroke platform who want a noticeable weight saving and a genuine performance lift over the standard muffler. Part number 45658.

• FMF Resonance Chamber Technology (RCT) applied internally and externally
• Anodised titanium canister with carbon fibre end cap
• Stainless steel mid-pipe
• Shorter overall length for reduced crash damage exposure
• Factory Forward Engineering positions the muffler closer to the motor to centralise mass
• Significant weight saving over the standard muffler
• Power gains throughout the RPM range
• RTS (Rapid Tuning System)
• Aerospace-grade materials, manufactured in FMF's Southern California factory
• Direct slip-on fitment for Sherco 250 FSE / 300 FSE

• FMF Factory 4.1 RCT slip-on muffler with carbon fibre end cap

Confirm fitment against your exact model and year before installing, and check the muffler clears the subframe, shock and bodywork.
Fit the muffler with the engine cold, seat the mid-pipe joint fully, then tighten clamps and mounting bolts evenly - snug, not overtightened, as titanium and carbon can be damaged by excessive clamping force.
After the first ride, re-check the clamps, mounting bolts and any retaining springs, then re-check them periodically as part of your normal pre-ride inspection.
Handle the carbon fibre end cap with care; it can crack or chip under impact or if bolts are overtightened.
Allow the muffler to cool fully before cleaning. Use warm soapy water or a dedicated non-abrasive metal or carbon-safe cleaner and a soft cloth - avoid harsh solvents, oven cleaners and abrasive pads.
Discolouration and a bronze or blue heat tint on the titanium is normal with use and is not a fault.
When washing the bike, plug the muffler outlet and avoid aiming a pressure washer directly into the outlet or at the packing seams.
The muffler is repackable - replace the internal packing when the note becomes noticeably louder, exhaust residue appears around the end cap, or performance drops off. Riding with worn-out packing reduces power and can damage the internals.
Avoid spraying chain lube, degreaser or fuel onto the canister, and clean off any overspray promptly.
Store the bike with the muffler dry; if the bike will sit for a long period, keep the outlet covered to stop moisture and pests entering.