I been Using internally standard 4agze with a Turbo aswell(twincharged) aswell running 30psi ,the motor had done 100 000km when i got it from the importers , Never replaced the std head gasket , put a very mild set of cams in it thats all 215kw @ the wheels its been in the Car for 8 years ,they are aprox 25kgs lighter than a Ca18, , Tuff engines in Std form . best $1000 race car engine i have had.
here are the outright Results http://thehill.noosacarclub.com.au/th ... ic%20Noosa%20Outright.pdf