Originally posted by Marcos.J
if you add a .1mm shim to the .3mm shim running with 30% will that give you more top end?
Yes it will, but for sure we are talking about 30% nitro content, if less % it will eat out bottom end and idle will unpredictable. So in every single particular case, head shimming needs to e adjusted. For instance, in Las Vegas you will not get away with stock shimming for sure.