Yoshimura R-77 Slip-On Exhaust | 15350AJ521. The growing 300cc entry level bike offerings are amazing these days. Take the brand new BMW G 310 R, a stunning bike that is ripe to go racing...enter Yoshimura R&D.We took our race bred R-77 profile and tuned it to the new Beemer's 310cc single cylinder performance needs. The end result is a Race Series system that creates 4.9% max HP and 5.6% max torque, while dropping over- Yoshimura R-77 Slip-On Exhaust | 15350AJ521.