Yoshimura RS-4 Stainless Full Exhaust with Aluminum Muffler | Honda CRF450X / CRF450L / CRF450RL 2019-2025

The Yoshimura RS-4 Stainless Full Exhaust System is a complete header-back exhaust for the 2019-2025 Honda CRF450X, CRF450L and CRF450RL, featuring a tapered stainless steel header, a pentagonal aluminum muffler with a carbon fiber end cap, a polyresonant duplex front chamber, and a stepped two-stage core baffle, and it accepts both spark arresters and sound inserts.

The RS-4 is the system that built Yoshimura's modern off-road reputation — the platform Ryan Dungey used to take the AMA 450 Supercross and Motocross championships in his rookie season. The engineering that matters here is the front chamber: the polyresonant duplex design tones the exhaust note down while adding power in the mid and high range, which is why the RS-4 can run a genuinely open two-stage baffle without being punishing on a trail bike.

The tapered header optimizes gas velocity through the range rather than chasing peak alone, and the pentagonal muffler shape maximizes internal volume within the space available beside the subframe. Spark arrester compatibility is built in, which matters on a CRF450X or 450L that spends its life on public land.

• Complete header-back full exhaust system
• Tapered stainless steel header pipe with aluminum muffler and carbon fiber end cap
• Pentagonal muffler profile for maximized internal volume
• Polyresonant duplex front chamber tones exhaust note while adding mid and top-end power
• Stepped, two-stage core baffle
• Spark arrester and sound insert compatible
• Considerable weight reduction versus the stock exhaust system
• Yoshimura part number 961-1215 (manufacturer part 224500D320)
• Made in the USA by Yoshimura R&D of America

Fits the 2019-2025 Honda CRF450X, CRF450L and CRF450RL fuel-injected models as a direct replacement for the complete stock exhaust. Note that it does not fit the CRF450R, CRF450RX or CRF450RWE — those motocross models use a different Yoshimura system.