Chris sorry for the late reply. I was not at that race but I have had in depth conversations about it with those who were. Pretty much all of the guys I talked to reduced their head shims slightly and ran 40% or left their shimming stock and ran 50%. Make sure you are running either 8.5 or 9 for insert. This should put you into the good power range without having to overlean the engine and reduce its life. The guys at that race were going lean on the needles trying to get pro power so to speak and thus flame outs were everywhere. Hope that helps.