Serco in Capalaba Brisbane are the Aus importers of Cometic - Almost Guarantee they will have a HG on the shelf - make sure you get the correct thickness - you may even consider dropping a couple of thou in size to raise your compression, then you shouldn't need to run as much boost to acheive a high HP... must be tuned on a dyno with good knock sensing and only every user 98RON....
 
I think standard is about 56 thou - you can go as thin as 27 thou with cometic.. 30 thou would raise your compression by about 0.5:1

Probably a dumb question, but I'm ordering the hastings rings of the net, my pistons are 1mm oversize, do you just use the same rings as standard size? Cause they dont give options for bigger rings. 

No, you need 1mm OS rings also.