Yoshimura · RS-12 · Full System
The Yoshimura RS-12 Signature Series Exhaust System is a full system built around an aluminum muffler for select KTM and Husqvarna 450 motocross models. Designed for Husqvarna FC450 2023–2027, KTM 450SX-F 2023–2027, and KTM 450SX-F-FACTORY-EDITION 2022, it brings Yoshimura’s RS-12 engineering to riders looking for a more connected feel and a strong, usable power character.
This RS-12 system features resonator technology in both the header and the muffler, along with fit-focused details like precision machined joints and an asymmetrical muffler profile for added clearance. A sound insert is included, while spark arrester options are available separately (see the table on the page).
Technology
This RS-12 full system incorporates a resonator on the header and in the muffler, a first for a Yoshimura production motocross exhaust. The tuned header resonator is designed to enhance power characteristics while improving sound, supporting a more connected riding feel on the targeted 450 models.
Performance
The RS-12 muffler uses an asymmetrical shape intended to maximize capacity and integrates a resonance chamber for managing sound and increasing usable power. Its distinctive profile is also designed to provide additional clearance for the tire and brake caliper on the listed KTM and Husqvarna applications.
Fitment
RS-12 systems utilize precision machined joints for an exacting fit, promoting a secure seal with full 360 degree contact. A patent pending Precision Taper Fit (PTF) insert ring is used to simplify installing and removing sound inserts and spark arresters, and the carbon end cap cover design is intended to improve durability and ease servicing.
Engineering
Yoshimura’s RS-12 Signature Series design pairs a tuned header resonator with a muffler resonance chamber to shape sound and power delivery for the specified KTM and Husqvarna 450 platforms. The system also focuses on packaging, using an asymmetrical muffler form for clearance and a tapered muffler body inlet intended to allow the system to be pushed forward for weight centralization without sacrificing performance.
Fitment
Built as a full system with an aluminum muffler, this RS-12 incorporates works-look matte carbon fiber end cap styling with Yoshimura’s detailing. The system uses precision machined joints, a construction approach Yoshimura notes is like the works systems used by its Factory Racers. The goal is a superior, exacting fit that better secures the seal between surfaces and supports system life, fit, and performance.
Sound
A sound insert, INS-30-K, is included with this RS-12 full system. Spark arrester options are available but not included, and the product uses a patent pending Precision Taper Fit (PTF) insert ring intended to make insert changes easier. For the exact insert and spark arrester codes associated with this system, refer to the sound insert and spark arrester table shown on the page.
Performance
This RS-12 system is specified for Husqvarna FC450 2023–2027, KTM 450SX-F 2023–2027, and KTM 450SX-F-FACTORY-EDITION 2022. The page includes resources to help with setup, including an installation PDF and a product video, plus a fitment table for quick confirmation. A dyno chart is also shown on the page for reference.
| Part Number | 264630S320 |
|---|---|
| Brand | Yoshimura |
| Product Line | Signature Series Exhaust System |
| Series | RS-12 |
| System Type | Full System |
| Material | Aluminum |
| Sound Insert (Included) | INS-30-K |
| Spark Arrester | Not included |
| Shipping Weight | 15 lb |
| Barcode | 00840025913769 |
| Emissions Compliance | QUALIFIED MANUFACTURER DECLARED "REPLACEMENT PART" |
| Make | Model | Model Years |
|---|---|---|
| Husqvarna | FC450 | 2023–2027 |
| KTM | 450SX-F | 2023–2027 |
| KTM | 450SX-F-FACTORY-EDITION | 2022 |
Fitment as listed by Yoshimura for part number 264630S320.
| Part Number | Type | Included With This System |
|---|---|---|
| INS-30-K | Sound Insert | Yes |
| SA-21-K | Spark Arrester | No |
| SA-20-K | Spark Arrester | No |
Instructions / What's Included (PDF)
Provided by Yoshimura. Opens in a new tab.
