Yoshimura RS-12 Full Exhaust System | Kawasaki KX450 2019-2023 / KX450X 2021-2024 | Stainless with Aluminum Muffler

The Yoshimura RS-12 Full Exhaust System is a complete header-and-muffler replacement for the 2019-2023 Kawasaki KX450 and 2021-2024 KX450X, built with a stainless steel header, an aluminum canister and a carbon fiber end cap.

Yoshimura's relationship with the KX450 is not a catalogue entry — the company has run the bike in AMA Supercross and Motocross as a factory-supported effort, and the production system comes out of that work rather than being adapted to it afterwards.

On a 450 motocrosser the full system is the meaningful upgrade over a slip-on. The header controls where the power arrives as much as the canister controls how much of it there is, and on a bike raced this hard the header geometry is where most of the development effort goes.

The RS-12 canister is shorter and more tightly packaged than the RS-9 and RS-4 that preceded it, which pulls mass forward and inboard from the widest, highest point on the machine.

• Complete system — stainless steel header and muffler
• Aluminum canister with carbon fiber end cap
• Compact RS-12 design centralises mass compared with earlier Yoshimura canisters
• Repackable core — serviceable rather than disposable
• Yoshimura part number 961-3417 (manufacturer part 244720S320)
• Made in the USA by Yoshimura R&D of America

Fits the 2019-2023 Kawasaki KX450 and the 2021-2024 KX450X. Kawasaki revised the KX450 exhaust for 2024 and Yoshimura builds a separate system for that generation — this is the earlier part, with the aluminum muffler. Check the sound and spark arrester requirements for the land you ride; a separate Yoshimura spark arrester insert is required for USFS and BLM areas.