FMF FACTORY 4.1 RCT STAINLESS MUFFLER WITH CARBON END CAP FOR 2020-22 KTM 350/500 EXC-F/ KTM 350/450/500 XCF-W, HUSQVARNA FE250/350/450/501, FE350S/FE501S  


In stock and ready to ship.


The Factory 4.1 RCT incorporates the latest in FMF Resonance Chamber Technology™ both internally and externally. In addition, we achieve a shorter overall length that is less susceptible to crash damage and complementary to our Factory Forward Engineering - moving the muffler closer to the motor to centralize mass. The Factory 4.1 RCT is constructed from only aerospace grade materials that meet our exacting specifications and is manufactured 100% at our Southern California factory.



-Available in Natural Aluminum Muffler with Carbon End Cap 

-Massive Power gains throughout the RPM range.

-Huge weight savings

-New RTS (Rapid Tuning System)

-FMF uses the highest quality proprietary blend of alloy grade titanium made especially to our standards.

-See Features Tab -> Fitment for header compatibility 

 Notice: Closed Course Use Only

Item ID: 045647

Type: Slip-On

Configuration: Single

Const: Aluminum

Finish: Natural

Midpipe: Stainless Steel

Endcap: Carbon

Spark Arrestor: Screen Insert (included)

Carb Warning: no

Quiet Insert: 94dB Insert (included)


This modification is 100% for Closed Course Competition Use only. Not Intended for Street Use!  Does not conform to CARB/ EPA laws and regulations and is not legal for use upon a highway.I understand that it is illegal to install an aftermarket part that is intended for use with, or as part of, a required motor vehicle pollution control device or system that alters or modifies the original design or performance of the motor vehicle pollution control device or system unless the part has an Executive Order from CARB. Installation of these types of parts which are not CARB‐approved on a pollution controlled motor vehicle in the state of California may result in the Department of Motor Vehicles (DMV) revoking the vehicle registration and certification of ownership (title), refusing the transfer of registration, and/or the vehicle failing smog inspection. It is illegal to operate a vehicle in California with an illegal aftermarket part. Law enforcement may cite you for the use of an illegal aftermarket part and seize your title and license plate. By ordering this product you agree to these terms.  You agree that Blais Racing Services only sells racing parts and parts for converting your bike into a closed course competition only vehicle and will not use Upon a Highway!