Yoshimura RS-12's Updated Spec on 2026 KX450 | Tested

At Yoshimura we never settle for good enough. Our engineers are always searching more performance on the daily. When challenged by our factory Kawasaki Red Bear off-road race team, we decided to dig deep and find more power for the Red Bear Kawasaki KX450.

Right away the results were astounding! Stew Baylor pulled his first GNCC holeshot in years when using the new spec system...

"Steward Baylor grabbed the holeshot and led the group into the woods on his KX™450X. After a strong battle down to the finish, Baylor was able to take the win, his second of the year. “I was surprised but stoked on the holeshot! I’ve only ever pulled two XC1 in my 12 years in the class. Getting out front early made a huge difference as I was able to keep my goggles and radiators clean. "- From Team Red Bear Factory Kawasaki Team PR

The refined power on the KX450 now produces up to 4.4% more HP @8,600rpm and up to 4.8% more torque @8,400rpm. No wonder this machine is pulling holeshots now!

"I am excited to announce the release of a system that I have been involved in developing over the past year. The focus of these changes was to enhance the performance that I felt the Kawasaki needed. After racing with this system and winning the last few events, I believe it is ready for consumers, and I am proud to have been a part of this project!" -Steward Baylor, team owner 2x World Champion, and now 6x National Enduro Champ

Our RS-12 muffler has loads of features including our PTF insert system that makes changing inserts a breeze and an optimized muffler shape with added volume and brake caliper clearance. Optional spark arrestor SA-21-K available separately.

Yoshimura's RS-12 systems proudly designed, developed and manufactured in Chino, California.

Rubber mounted RS-12 muffler dampens vibration to subframe
Aggressive intelligently designed, the RS-12 asymmetrical shaped muffler allows maximize capacity and incorporates a resonance chamber for managing sound and increasing usable power. RS-12's unique profile also provides more clearance for tire and brake caliper.
Improved performance gains with refined power delivery.
Just like the works systems our Factory Racers use, RS-12 systems utilize precision machined joints. Machined joints provide a superior and exacting fit for joints by better securing the seal between two surfaces with a perfect 360 degree contact surface which translates into improved system life, fit and performance.
New patent pending Precision Taper Fit (PTF) insert ring makes it easy to install and remove sound inserts and spark arresters.
Works-look matte carbon fiber end cap with industry leading design, innovation and detailing as expected from Yoshimura.
Carbon end cap covers the RS-12 inner cap, thus improving looks, while providing easier service as compared to other sandwich mounting designs most commonly found in the industry.
Repack Kits, optional Inserts and Spark Arresters are available for all models

Rocky Mtn Red Bear Kawasaki KX450F 2025 Collection

KX450/X 24-26 RS-12 Stainless Full Exhaust, w/ Stainless Muffler