'08 STi ECU is very different from '06/07 (and before)....SI Drive etc, etc.
Also '08 STi has VVT on exhaust valves.
'08 STi does not have a twin scroll turbo.
ECUTek is the only available reflash for '08 STi at the moment (and for the forseeable future)...there are two ECUTek tuners in WA...Maximum Motorsport and Race Torque.
Cannot comment on compatability of MoTeC or Autronic, though I understand one of the Oz-spec MY08 STi's currently doing the dealer display circuits is going to Autronic.
When getting advice on upgrading the '08 STi ECU, be sure you understand the difference between "should be" and "can do".