01-06 HONDA CBR600F4I: Two Brothers M-2 Black Series Slip-On Exhaust (Carbon Fiber) Rule the track with the new subtly sophisticated exhaust: The Black Series. The Two Brothers Racing Black Series exhausts downplays the raw power these systems unleash. Dyno tuned and track tested, like all TBR exhausts, the Black Series are aimed at those who want Absolute Top Level performance but smart and understated aesthetics. Black Series systems are fitted with black bands, black inlet / outlets, and a black endcap. Adding this Two Brothers Racing high-performance Black Series exhaust system will help you gain additional horsepower and increase torque while lowering the overall weight of your bike.