You guys are wasting too much time. If you're that bloody worried about the legal aspects, go and get a non turbo for now. They still go better than the average commonwhore (not to mention look shit loads better), insurance with be cheaper, and they're P plate legal. Then when your off ya Ps, sell it and get a turbo.
Remember if the car is modified and certified to have less than 125kw per tonne, theres nothing stopping you from changing it back once you get the all clear. If you were pulled over or had a stack and they found mods that make the car go faster (instead of slower), your stuffed basically.