skimmed

After having my headgasket go just before i started my hybrid build, my head now needs skimmed... according to my mate who checked it at his work it needs 8 thou taking off. Will this muck up my cr ratio? I have considered trying to find a thicker headgasket to compinsate for the...

As im having the head gasket , cambelt etc done...im also having the head skimmed...the garage that are doing said that they could skim it by 4mm as it will increase the combusion ratio or something like that.... any ideas what gains id get mines a 2L8v