Is that 15psi overboost? If so, it will be holding 11-12psi, right?
That's not too far off the stock boost, I'd leave the stock gasket as is.
You can get thicker gaskets made if you feel adventurous, something like 1.5mm would be a nice half-way house.
Different size gaskets also affect the cam timing, so be careful.
yeah i was thinking thicker cos the head has just had ten thou skimmed off it, and that was the second time its been skimmed. im just worried that this will have pushed the compression up a bit when i want it down a bit!