Yoshimura RS-4 Stainless Slip-On Exhaust with Aluminum Muffler | Yamaha YZ250F / YZ250FX / WR250F 2019-2022

The Yoshimura RS-4 Stainless Slip-On Exhaust is a bolt-on muffler for the 2019-2022 Yamaha YZ250F, 2020-2022 YZ250FX and 2020-2022 WR250F, featuring 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 polyresonant duplex front chamber is what distinguishes the RS-4 from a simple straight-through canister. Working together with the stepped two-stage baffle, it lowers the sound level while lifting power through the mid range and top end — the opposite of the usual trade where noise is the price of power.

The pentagonal muffler shape maximizes internal volume in the space available beside the subframe, and spark arrester compatibility means the same muffler covers both a moto track and public land. This is the slip-on version, retaining the stock header, so it is the accessible entry into the RS-4 platform.

• Bolt-on slip-on muffler — retains the stock header
• Pentagonal aluminum muffler with carbon fiber end cap
• Polyresonant duplex front chamber lowers sound while adding mid and top-end power
• Stepped, two-stage core baffle
• Maximized internal volume for sound control at full flow
• Spark arrester and sound insert compatible
• Yoshimura part number 961-6415
• Made in the USA by Yoshimura R&D of America

Fits the 2019-2022 Yamaha YZ250F, 2020-2022 YZ250FX and 2020-2022 WR250F as a direct bolt-on to the stock header, and is the standard muffler upgrade for YZ250F motocross and YZ250FX/WR250F cross-country and enduro race builds.