actualy they do have an issue with insurance, no insurance companies will touch you with a 10ft pole if your a P plater and want to insure a skyline, the rule is that if you got your Ps before june 07 or wenever it is, you are under the power to weight ratio rule, witch is no more than 125kw per ton, R33 with a turbo are 133kw per ton, and R32 with a turbo are 122kw per toni think.
If you got your Ps after june 07 then you arnt allowed a turbo or supercharged or V8 at all.
Im pretty sure this is what the rules are, if im wrong please someone correct me.
Hope this helps