my mate has just blown his head gasket on his 20 ecotec cav. The head is warped and it has been skimmed before and because the compreesion ratio is allready 10:8 having another skim will cause premature detination. the feller who is skimming the head said he will have to use a shim inbetwwen the head and the block and i dont like the sound of this. So i have found a Red top and i want to know if this will go straigth on the x20xev blockwith out changing any thing else sombody please help!!!!!