you NEED new studs with a Pro design cool head. the stocks are not long enough. and you do NOT need studs with a Noss machine head. there are acouple other makers of cool heads but i dont know much about them. maybe someone else will chime in and give some more info. oh yeah your probably going to need new Orings aswell with the head. these are your gaskets and could definatly mess up your motor if they are streched or bad.