Well RR have done years of tune testing I thing Rafi was the one to crack the ecm in these cars (don't quote me) USA has just as many weather conditions as OZ if not more(and he can tune the ECM to any fuel type). My car was not dyno tuned it was flash tuned which is a generic tune, it took less than 1/2 a day to do a flange mod, dyno before and after, plus he put the wrong idle tables in causing the car to break down on the way home.(which cost me a lot in $ and stress he did eventually paid 1/2 my towing fees so generous of him) I am a mechanic and I new what the problem was as I had my scan tool with me, ooh but no it couldn't be the tune (says sonny). His tune does not increase throttle response only above 3600rpm, NO gearbox parameters are changed, NO rev limit changed, NO ECL delete. I have personally spoken to Rafi about a tune for OZ and he assured me there would be no problems with a RR tune in OZ as you have to give him the commuter model number for every single car, because there a some variations for different models.(He has sent tunes to a few place outside the USA and had NO problems, send him a email) I have had 2 HSV,s dyno tuned and it takes a day to get them perfect on the dyno 1/2 a tank of petrol is used and then road tested for 45 minutes, my ISF had maybe 5 litres used and a 5 minute test drive. And no I have not seen a RR tune in OZ if I had my time over I would have gone RR as they know a hell of a lot more about these cars than any one in OZ.