I would hazard a guess that our cars are spec'd for a viscosity of ~7 cST @ 100C, based on the fact that the stock 0W-20 is rated for that. So in saying that, our cars run hot when being beat on, that raises the temp up to 110-120-130 degrees celsius, so from that I would conclude that the stock 0W-20 at those temps drops to a viscosity rating of ~4-5 cSt which in my mind is not good. but if ya want to keep using the OEM Mobil 0W-20, that I would think having a thermostatically controlled oil cooler would be good investment.
see my post:
http://www.ft86club.com/forums/showthread.php?t=63955
EDIT: this doesn't tell you what pressure you will get, but will give you an idea of what oil you should run based off temp to ensure oem designed oil pressure is maintained.