Smaller turbo like a TO4z, shit thats still a massive turbo. If you have any lag it will be slow. Circuit racing is not about peak power, its about getting in and out of corners as fast as possible. If you have to wait for power you are no mans land.
I would think a GT35 or similar is more than ample.
Forget the A048's, they would have to be worst (slowest) R Comp tyre in Australia. And only becasue you cant get medium compound in anything over 16". So for 17" and over rims your only choice will be medium hard (MH), they are ok when new for the first 2 laps then fall off big time, after 3 sesions they will be as hard as truck tyres.
Go for Yokohama AO50 or Bridgeston RE55.