Yoshimura · AT2 · Full System
The Yoshimura R9 25-26 Race AT2 Stainless Full Exhaust is a Race Series Exhaust System full system engineered specifically for the Yamaha YZF-R9 2025–2026. Built around Yoshimura’s AT2 muffler design, it’s aimed at riders looking to sharpen the bike’s power delivery while dropping significant system weight.
Yoshimura reports performance gains throughout the power spectrum, paired with the distinctive AT2 exhaust character. This system also brings a cohesive, finished look from the headers through the tail pipe, and includes a custom carbon fiber heel guard for a clean, purposeful appearance. Fitment details are shown in the fitment table below.
This AT2 Race Series full system includes manufacturer-verified performance data for the Yamaha YZF-R9 2025–2026. Yoshimura reports "up to 4.68% HP gain @10,000 RPM" along with a "3.14% torque increase @7,100 RPM". Reference the dyno chart shown on the page for the full curve.
The stock system is stated at 16.0 lbs, while the Yoshimura AT2 Race Series Full system is listed at 10.7 lbs. For riders focused on a more responsive feel, trimming weight at the exhaust can be a meaningful upgrade.
For riders who want clear expectations, Yoshimura provides sound readings using J2825 standards in an open configuration with no sound insert. The listing includes results at 2000 rpm and 5000 rpm, shown as Stock and AT2 values. Sound insert options are also listed in the insert table on the page.
Engineering
This system is part of Yoshimura’s Race Series Exhaust System lineup and uses the AT2 series muffler in a complete full-system configuration for the Yamaha YZF-R9 2025–2026. Constructed in Stainless, it’s designed as an integrated package from the header section through the tail pipe, built to deliver the results Yoshimura developed specifically around the R9 platform.
Performance
Yoshimura positions the AT2 Race Series system as a way to give the R9 stronger pull across the power range. The manufacturer’s verified performance claims include "up to 4.68% HP gain @10,000 RPM" and "3.14% torque increase @7,100 RPM".
Materials
Along with performance, this AT2 system is presented with a cohesive visual package, described by Yoshimura as featuring a Works Finish from the headers to the tail pipe. A custom carbon fiber heel guard is also noted, adding a purposeful detail where the rider interacts with the bike. Product photos and video on the page provide a closer look at the overall shape and styling.
Fitment
This full system is listed for Yamaha YZF-R9 2025–2026 only, and the on-page fitment table should be used to confirm the application. The page also includes an installation PDF for step-by-step guidance during setup. Yoshimura additionally notes an AB Bracket kit option for riders who elect to remove the passenger pegs.
Figures as reported by Yoshimura.
| Part Number | 13900AP520 |
|---|---|
| Brand | Yoshimura |
| Product Line | Race Series Exhaust System |
| Series | AT2 |
| System Type | Full System |
| Material | Stainless |
| Shipping Weight | 18 lb |
| Barcode | 00840025918641 |
| Emissions Compliance | QUALIFIED MANUFACTURER DECLARED "MODIFIED PART" |
| Make | Model | Model Years |
|---|---|---|
| Yamaha | YZF-R9 | 2025–2026 |
Fitment as listed by Yoshimura for part number 13900AP520.
| Part Number | Type | Included With This System |
|---|---|---|
| INS-27-K | Sound Insert | No |
| INS-20-K | Sound Insert | No |
| INS-35-K | Sound Insert | No |
Instructions / What's Included (PDF)
Provided by Yoshimura. Opens in a new tab.
