Yoshimura · Full System
The Yoshimura GP-MAGNUM Stainless Full System is a Race Series Exhaust System built to match the Honda Monkey’s classic look while delivering the distinct GP-Magnum style. Designed for builders and racers who want a retro Yoshimura JDM-inspired appearance, this full exhaust system uses stainless construction throughout and features an old school Yoshimura badge.
Built specifically for Honda Monkey 2019–2026 (see fitment table below), this U.S.-marked configuration is tailored for the U.S. market. Yoshimura lists the GP-MAGNUM Stainless Full System weight at 5.3 Lbs. versus the stock full system weight of 11.2 Lbs.
This GP-MAGNUM is a complete Full System in Yoshimura’s Race Series Exhaust System line. The manufacturer states stainless steel construction is used throughout the system, pairing classic mini-bike proportions with the recognizable GP-Magnum shape and an old school Yoshimura badge.
Yoshimura explains this exhaust was designed specifically for U.S. spec. bikes and is made and marked for the U.S. market. Yoshimura R&D is identified as the only authorized distributor in North America for Yoshimura Japan (YJP) and Yoshimura Asia (YAT).
Yoshimura provides clear weight numbers for comparison: GP-MAGNUM Stainless Full System weight is listed at 5.3 Lbs., while the stock full system weight is listed at 11.2 Lbs. These stated figures help riders understand the change in system weight.
Yoshimura positions the GP-Magnum as a natural match for the Monkey’s late 60’s early 70’s retro styling. The look is aimed at builders and racers who want that classic Yoshimura JDM style on a compact platform, finished off with an old school Yoshimura badge for a period-correct touch.
Engineering
According to Yoshimura, two GP-Magnum mini systems are available and both are handcrafted by a sister company in Asia for Yoshimura R&D exclusively for the U.S. market. The manufacturer states the system uses stainless steel construction throughout, with two sleeve options: a stainless polish finish or a titanium sleeve that displays a bluing effect.
Fitment
This exhaust system is listed for Honda Monkey 2019–2026. Media on the page includes a dyno chart, a product video, and an installation PDF to support setup and expectations. Yoshimura also notes a right side cover is available but sold separately.
| Part Number | 121300U500 |
|---|---|
| Brand | Yoshimura |
| Product Line | Race Series Exhaust System |
| System Type | Full System |
| Material | Stainless |
| Shipping Weight | 10 lb |
| Barcode | 00840025909984 |
| Emissions Compliance | QUALIFIED MANUFACTURER DECLARED "MODIFIED PART" |
| Make | Model | Model Years |
|---|---|---|
| Honda | Monkey | 2019–2026 |
Fitment as listed by Yoshimura for part number 121300U500.
Installation Instructions (PDF)
Provided by Yoshimura. Opens in a new tab.
