trx 2.5 is decent motor. I have tuned a couple and now I will be tuning up my freinds 2.5r. I feel confident that it all comes down to break in and proper running of the motor therafter. yes it is a powerful lil mill that can be a little finicky in the hands of the inexperienced, but with proper know-how it can produce many gallons of fun and exitement. They released 33% for the 2.5's simply cause they become more efficient power producers and actually run cooler than with 20%. Pretty smart from a company that has had a bad rep from bad tuners saying that they burned out their motors in a 1/2 gallon or so. This new fuel should give great power and cooler temps out of almost any motor.