Starting to think about the next engine mod I want and it's the heads from my spare engine. Few questions though. I need to know how much I can shave the heads before i have preload issues. Most of the rockers have around 1/3 - 1/2 a turn but some have 3/4. How much can i safely shave off without looking for new rods? Also I don't want to go sick on comp, incase i decide I want boost down the track. Other question is on porting what should I tell the bloke I want as i don't want to lose much bottom end. Should I have anything done to the intake manifold or just leave that? I'm sure I will have more questions as I get closer to dropping the heads off.