Yoshimura RS-3 Race Stainless Full Exhaust System | Honda Monkey 125 2019-2026 | Closed-Course Competition

The Yoshimura RS-3 Race Stainless Full Exhaust System is a complete closed-course header-back exhaust for the 2019-2026 Honda Monkey 125, featuring an oval stainless steel muffler with a straight single-core baffle, a high-temperature ceramic-coated end cap with a titanium tip, and an integrated heat shield, producing a 7.3% gain in peak horsepower while cutting system weight from 11.2 pounds to 5.5 pounds.

The Monkey's stock exhaust is heavy and heavily restricted, so a full system is the single most effective change available to the platform. The RS-3 replaces header and muffler together, and its custom-developed inner core baffle is tuned specifically for the 125cc single rather than adapted from a larger system — which is why the gains show up as a 7.3% horsepower and 3.1% torque increase rather than just added noise.

An 18mm O2 sensor bung comes installed, so the factory sensor relocates without adapters or a check-engine light. The system is designed, developed and manufactured by Yoshimura R&D of America in Chino, California.

• Complete header-back full exhaust system — replaces stock header and muffler
• Oval-shape stainless steel muffler with maximized internal volume
• High-temperature ceramic coated end cap with titanium tip
• Straight, single-core baffle; accepts optional low-volume sound insert
• Integrated heat shield and 18mm O2 sensor bung installed
• 7.3% increase in peak horsepower and 3.1% increase in peak torque
• 5.5 lb system weight versus 11.2 lb stock — a 5.7 lb saving
• Yoshimura part number 960-2272 (manufacturer part 12130A5500)
• Made in the USA — for closed-course competition only, not intended for street use

Fits the 2019-2026 Honda Monkey 125, including ABS models, and is the standard full-system upgrade for Monkey builds used in minibike racing, pit-bike classes and closed-course track days.