Yoshimura · RS-12 · Slip-On
The Yoshimura RS-12 Race Series Exhaust System is a stainless slip-on built for Honda CRF300L 2021–2026 and Honda CRF300L-Rally 2021–2026. Designed to sharpen the character of the 286cc single, it delivers the signature Yoshimura tone while trimming mass compared to the stock muffler.
Yoshimura reports verified performance gains of "up to 7.0% HP gains at 5" and "7.5% torque boost at the same peak – pe". With a slim, trail-ready layout and documented sound testing details referenced on the page, the RS-12 is a focused upgrade for riders who want a straightforward slip-on change with measurable results.
Engineering
Built as part of Yoshimura’s Race Series Exhaust System line, the RS-12 slip-on is engineered to bring a more purposeful feel and sound to the CRF300L and CRF300L-Rally platform. Its stainless construction and RS-12 series design target dual-sport riders who want a performance-minded exhaust without changing the entire system.
Performance
This RS-12 slip-on comes with manufacturer-verified performance statements shown with the dyno information on the product page. Yoshimura reports "up to 7.0% HP gains at 5" and "7.5% torque boost at the same peak – pe", giving riders published performance targets to reference for the CRF300L/Rally setup.
Sound
Sound levels are referenced using J2825 standards with SA-20-K Spark Arrestor installed. The listing includes specific dB figures at 2000 rpm and 5000 rpm for stock and the RS-12 slip-on, helping riders understand the change in sound output with the configured setup shown on the page.
Performance
Yoshimura positions the RS-12 slip-on as a practical performance upgrade, pairing published performance claims with a lighter muffler weight than stock. Yoshimura reports "up to 7.0% HP gains at 5" and "7.5% torque boost at the same peak – pe". The listing also states a muffler weight of 7.3 lbs compared to a stock muffler weight of 10 lbs, reinforcing the system’s weight-conscious approach.
Sound
The sound insert and spark arrester table on the page outlines available options and how the exhaust is configured. SA-20-K is shown as installed, while INS-34-K is listed as not included. The product’s sound information is presented in relation to J2825 standards with SA-20-K Spark Arrestor installed, with rpm-based sound data included in the listing for additional context.
Installation
To help riders evaluate and install the RS-12, the product page includes multiple photos along with a dyno chart, a product video, and an installation PDF. Those resources provide a clear look at the system, the manufacturer-published performance presentation, and the installation documentation, all in one place for the CRF300L/Rally application.
Figures as reported by Yoshimura.
| Part Number | 123412S520 |
|---|---|
| Brand | Yoshimura |
| Product Line | Race Series Exhaust System |
| Series | RS-12 |
| System Type | Slip-On |
| Material | Stainless |
| Spark Arrester | Not included |
| Shipping Weight | 12 lb |
| Barcode | 00840025919495 |
| Emissions Compliance | QUALIFIED MANUFACTURER DECLARED "MODIFIED PART" |
| Make | Model | Model Years |
|---|---|---|
| Honda | CRF300L | 2021–2026 |
| Honda | CRF300L-Rally | 2021–2026 |
Fitment as listed by Yoshimura for part number 123412S520.
| Part Number | Type | Included With This System |
|---|---|---|
| SA-20-K | Spark Arrester | Installed |
| INS-34-K | Sound Insert | No |
Instructions / What's Included (PDF)
Provided by Yoshimura. Opens in a new tab.
