Rich, I just jumped on to this topic to see what everyone had to say about race fuel for their YZ400/YZ426 bikes. We have a YZ250F that we race moto-x with in the 125 intermediate class (my son does the racing). You mentioned that a racer would feel increased throttle response (probably the same kind of difference we felt when putting race gas vs. pump in our 00'YZ125), and a power difference over 6000RPM. My son is on the rev limiter most of the time. I've wanted to use race gas, but have 7 questions. #1 Does race gas hurt the motor like Motocross Action Magazine says? #2 Does jetting changes associated with race gas only require only a main jet change? #3 I think either Sunoco or VP have a leaded race gas. Would that be better from a reliability standpoint? #4 Would mixing 50% race gas/50% pump be worth the benefit? #5 Will race gas produce less carbon build up on the valves? #6 I live close to a VP distributor which VP gas would you suggest? #7 Do you believe that race gas shortens the life expectancy of the motor? Thanks in advance for your answers.