We developed the RS-4 in the R&D lab called the Motocross track. The RS-4 boasts its own resonance chamber and utilizes its volume and a unique baffling system to create the sound and power that is purely Yoshimura. With 450's it's not all about creating more power, it's about creating more usable power and the RS-4 makes it happen. Max power is increased by 2.3% and max torque is increased by 1.2% throughout the power curve. Grip it and rip it!
Proudly made in the USA.
* Yoshimura Stainless Full System weight: 6.6 lbs. vs Stock Weight: 8.1 Lbs
This product was designed to fit on a standard equipped motorcycle, as delivered from the factory. OE and Aftermarket accessories not found on a bike as delivered from the factory, may not be compatible with this product.
Attention International Customers: This product was designed and tested to be compatible with vehicles in the U.S. marketplace only. Compatibility including fitment and performance may vary by marketplace.
Sound levels at idle speed tested at 1' above and 1' behind each
muffler on the same 21' 500 EXCF tested back to back.
Stock muffler 82
Stock w Pro Moto end cap / ultra silent insert 85
Stock w Pro Moto end cap / silent insert 86
Stock w Pro Moto end cap 88
Graves Motorsports w db killer 85
Graves Motorsports 89
Fmf q4 84
Fmf 4.1 88
Fmf power core 88
Lexx w db killer 86
Lexx w spark arrestor insert 87