The FMF Factory 4.1 RCT is a slip-on exhaust muffler for the specified Honda CRF450 models. It replaces the muffler section, not the complete exhaust system.

Features

• Resonance Chamber Technology (RCT) is incorporated internally and externally.
• The shorter muffler sits closer to the engine and is designed to be less exposed to crash damage.
• Features FMF’s Rapid Tuning System (RTS).

Specifications

• Aluminium muffler body.
• Stainless-steel midpipe.
• Black carbon end cap.

Kit Contents

• Screen-type spark-arrestor insert included.

Manufacture

• Manufactured at FMF’s Southern California factory.

Ordering Information

• Check header compatibility before ordering.
• FMF lists a different slip-on, part 041602, for 2021–2026 CRF450R and CRF450RX models; do not extend this part’s stated fitment to those years.

Cross-Reference OEM Part Numbers

• FMF: 041638.

Vehicle Fitments

• Honda CRF450R — 2027.
• Honda CRF450RX — 2027.