well i have type r turbo and its not internal build yet. so till then i was thinking about putting in a thicker head gasket and boosting somewhere around 10 to 15 psi. so my Q is what kind and how thick of head gasket would you suggest . i was thinking cometic . but not sure on how thick. some import shop has a 4milimeter thick one and i was thinking that would be too thick. what you guys think. thanks/