turbo will require engineering report. essentially any aspect that you modify that changes the cars original characteristic (from a safety POV) then you will need engineering. eg, brakes, seats(yes its messed), turbo, s/c, wheels (if greater than certain size allowments) etc etc, i'm not familiar with the rules up in QLD, but jsut ring up the RTA and they will usually point you to some literature that states it all...
Cheers
ps goin all motor is better as it'll mainly be internals that you change, until u decide to put on Individual Throttle Bodies