Well I'm of to see the dealer this arvo and will get them to check the ECU to find out what codes I'm getting.
Optimuck apparently has an appalling name for RON fluctuations
so BP seems to be the preferred drink of choice. GTs love 95 RON and over so going on GTClouds suggestion may do the Ultimate thing and run on that.
Thanks everyone for the feedback....I have also heard that a dodgy knock sensor can make it go bang if you go fang....