Hey man i went throught the same investigation process as u, was on phone to vic roads and just cars.
Basicly the R32 Gts-T is just under the power to weight ration ist comes in at 124.03 kw / tonner and ur aloud to have 125 kw per tonne.
However put on an exhuast and u will bump urself over the limit, and the guys from vic roads said, that ones the vehicle has had any performance modifications increasing the vehicles power it must be re assesed by vic roads and certified as a P plate legal vehicle.
As ppl have said yeh you will prbly get away with it.
However, INSURANCE, in the event of a claim, and ur car is over the limit and not certified by vic roads as a P plate car, then you claims will be rejected.
So unless u riding completely stock, you may get away with P/W, you will get insurcance, however you wont be coverd.
Call vic roads and Just cars to verify what i have said.
And anyone that dosnt believe me about insurance, wip out that fat policy you got when u insured your car and have a read. if you cant find it cal just cars.
Alot of ppl are cruising around un insured but are unaware of it, and pay a massive premium for nothing.
And yeh ive heard of ppl geting a payout, lets just say they were lucky, cos if insurance can find a way as easy as power to weight to get out of a payment, by all means they will.
SO in conclusion man, Stock its legal, Modfiied in anyway that increases performance it is illegal, you may get away with fines but will not be coved with insurance.
pz.