Yoshimura · RS-12 · Full System
The Yoshimura RS-12 Stainless Full System is a Signature Series Exhaust System built to sharpen power delivery on the Kawasaki KX450F 2024–2026 and Kawasaki KX450X 2024–2026. Developed through Yoshimura’s ongoing performance testing, this RS-12 full system pairs an updated muffler design with fit-focused joints and service-friendly insert hardware.
Key highlights include a rubber mounted RS-12 muffler to help reduce vibration to the subframe, an asymmetrical muffler profile that adds capacity while improving tire and brake caliper clearance, and Yoshimura’s Precision Taper Fit (PTF) insert system for easier sound insert and spark arrester changes. See the fitment table below for exact applications.
Installation
The RS-12 muffler is rubber mounted to help dampen vibration to the subframe. This detail is designed to reduce the transfer of vibration through the mounting points while supporting a secure, stable installation on the intended KX450F and KX450X applications.
Performance
Yoshimura’s RS-12 asymmetrical muffler shape is engineered to maximize capacity and integrates a resonance chamber for managing sound while increasing usable power. The distinctive profile is also shaped to provide additional clearance for the tire and brake caliper.
Sound
A patent pending Precision Taper Fit (PTF) insert ring is used to simplify installing and removing sound inserts and spark arresters. Yoshimura also notes that repack kits, optional inserts, and spark arresters are available for all models.
Engineering
This RS-12 full system uses precision machined joints similar to the works systems used by Yoshimura factory racers. Yoshimura states that these machined joints are designed to secure the seal between two surfaces with full 360 degree contact, supporting fitment accuracy and overall system life. The muffler is finished with a works-look matte carbon fiber end cap, and the carbon end cap covers the RS-12 inner cap to improve appearance while providing easier service compared to common sandwich mounting designs.
Performance
Yoshimura reports verified gains from the refined power delivery on the KX450 platform, with up to 4.4% more HP @8,600rpm and up to 4.8% more torque @8,400rpm. This updated specification was tested and developed alongside off-road racing efforts on the KX450X, with Yoshimura highlighting race-proven development feedback that guided the focus on enhanced performance for the Kawasaki setup.
Sound
Designed specifically for Kawasaki KX450F 2024–2026 and Kawasaki KX450X 2024–2026, this stainless full system centers on an optimized RS-12 muffler shape with added volume and improved brake caliper clearance. For riders planning to tailor sound or configuration, the RS-12 platform supports interchangeable inserts through the PTF system, and Yoshimura notes an optional spark arrestor SA-21-K is available separately. Reference the installation PDF shown on the page for guidance.
Figures as reported by Yoshimura.
| Part Number | 244730S521 |
|---|---|
| Brand | Yoshimura |
| Product Line | Signature Series Exhaust System |
| Series | RS-12 |
| System Type | Full System |
| Material | Stainless |
| Shipping Weight | 19 lb |
| Barcode | 00840025919983 |
| Emissions Compliance | QUALIFIED MANUFACTURER DECLARED "REPLACEMENT PART" |
| Make | Model | Model Years |
|---|---|---|
| Kawasaki | KX450F | 2024–2026 |
| Kawasaki | KX450X | 2024–2026 |
Fitment as listed by Yoshimura for part number 244730S521.
Instructions / What's Included (PDF)
Provided by Yoshimura. Opens in a new tab.
