Just wondering if I need to adjust the head shims on a .21 P5XLT if I am runinf 30 % nitro. The manual is kinda vague just referring to the "exploded view". The way I read the manual 25-33% nitro run the standard shims? Just a bit unsure any help would be much appreciated. I would just run 25% but I was running 30% in my last motor and I would hate to waste 1/2 a gallon of 30% fuel. Thanks so much!