Yoshimura RS-4 Stainless Slip-On Exhaust with Aluminum Muffler | Yamaha YZ450F / YZ450FX / WR450F 2014-2018

The Yoshimura RS-4 Stainless Slip-On Exhaust is a bolt-on muffler for the 2014-2018 Yamaha YZ450F, YZ450FX and WR450F, 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 straight-through canister. Working with the stepped two-stage baffle, it lowers the sound level while lifting power through the mid range and top end — a genuinely useful combination on a 450 motocrosser, where sound testing at race events is routine.

The pentagonal muffler shape maximizes internal volume in the space available beside the subframe, and spark arrester compatibility means the same muffler covers a moto track and public land. This is the slip-on, retaining the stock header.

• 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
• Spark arrester and sound insert compatible
• Yoshimura part number 961-6409
• Made in the USA by Yoshimura R&D of America

Fits the 2014-2018 Yamaha YZ450F, YZ450FX and WR450F as a direct bolt-on to the stock header, and is the standard muffler upgrade for YZ450F motocross and YZ450FX/WR450F cross-country and enduro builds. Fit an approved spark arrester insert before riding on US Forest Service or BLM land.