The head gasket has gone in my V4 STi after looking for gaskets i have seen difference thickness. Which one should i get?

 

If i well remember, OEM uses 1.6mm gaskets.
Did you ever skimmed heads/bloks?

Maybe can worth increase a bit the cr using thiner one's?

 

look at www.cometic.com i've just done my gaskets on my 2.5 wrx , they are 0.1mm thicker then standard gaskets and will hold more boost. much better then standard gaskets

 

1.6mm head gaskets will be fine, go for the metal type. But as soon as you begin skimming various engine faces then you will have to query it further dependent on how much material is removed.

There is usually plenty of piston to valve clearance but then theres nothing like being sure.