what would the benefit of 1.6mm steel multi layer head gaskets would have over 0.6mm ones?

What model/year is your car?

Lower compression which will allow you to run higher boost levels abit safer but you'll lose abit of response. You'd drop a bit of power too but people get that back with higher boost levels. Changing h/gasket thicknesses should only really be done on cars that can be mapped. Early classic turbos usually ran 1.6mm headgaskets as standard anyways and afaik, it was only late classic STIs that used the 0.6mm h/gaskets. Thats my 2p worth anyways

my car is a 93 wrx and if thats true about early classics i think ill go for the 1.6 then.

Thats not concrete mate lol, jonny/drew/finn/andyk should be able to confirm for definate but if my memory serves me right, it should be 1.6mm.

defo 1.6. only use quality gaskets ie, subaru, cometic or cosworth, almost all the others r rubbish

Andy

What do you think of these Andy here is a eBay item no 350446219198

cometic will be well up to the job mate

Genuine subaru ones are only about £90 though from importcarparts