how thick are the factory ones? i have a gen 2 MR2 3sge..that i'm rebuilding..and i want to run a little more comp..and i was planning on decking the head a little and using a TRD .8mm head gasket..but i don't think that running much more than 10.5 would be good on a street/pump fuel engine..so i want it to be as accurate as possible..