Quick update.
Fixed the broken boost solenoid, fitted an Akrapovic exhaust system and thanks to Aaron @ Import Monster got a great new set of shoes (Volk G12's)
Got a chance to get back to Phillip Island and did some tyre testing on the weekend.
Have now compared Bridgestones, Dunlops and the R888's and the R888's are by far the best of the 3 available 20" options right now - for sprint work at least.
Managed to improve my PI time to 1.46.75 - which is even better than my used A050's time. Car is still only running 15psi.
Have an intercooler, intercooler pipe kit and MAF sensor coming from AMS and will upgrade the intake pipes to 2012 OEM and see if we can't increase the boost some more.