Originally Posted by beidle99

No need to change head shims for a while. Keep the stock shims (IIRC total .8) until you start to loose performance. Once that happens swap a .2 shim for a .1 so you have .7 total. I havn't felt any performance drop and my plus 4 and it is almost finished its 5th gallon. Just remember to always preheat before starting and the engine wil last a long time.