181.3 hp @ 7lbs boost,these engines make a lot more horsepower with less boost then twin cylinder engines, the only thing I can contribute it to is one extra cylinder and for more valves..
RSR Performance
Have you taken the Yamaha out to the hill and tried it yet ??
No, wish I could have but the owner needed to get back over the hill and back to work, he took a few days off work and stayed in the hotel while I install the kit for him