Yoshimura has been the official exhaust supplier to Team Honda Red Bull Racing for several years now. All of that experience has helped Yoshimura in making an exhaust that complements an already great bike. The RS-4 not only increases power and is light, but it also has a lower centralized mass coefficient to provide better handling. Additionally, an overall improvement to the big Honda's power delivery was also realized. 

The RS-4 is a pentagonal shaped muffler that features a carbon fiber cone end cap, two staged stepped baffle and striking good looks. A tapered header pipe design is used for optimal flow and performance. The RS-4 muffler features a new front cap design that functions as a polyresonant chamber. This design makes for a quieter muffler with improved mid to top end power. The pipe also comes with 99 and 94dB inserts for AMA Pro and other racing requirements.