I was curious too so I did a little digging on the QLD/TMR site and I found this:
Moderately-Powered Vehicle Grounds
You may apply for a certifi cate of exemption if the car you wish to
drive was manufactured before 1 January 2010 and has:
• a supercharged or turbocharged engine, not diesel powered
• a power-to-weight ratio of not more than 125kW/tonne
• no other features of a HPV listed on this form.
You application must be supported by:
• a document published by the manufacturer verifying the
power-to-weight ratio, such as the owner’s manual or
information from the manufacturer’s website; or
• a specifi cation information test report.
A specifi cation information test report is issued by an automotive
service provider and must show:
• the name and address of the organisation(s) that conducted the
test(s)
• the date of the test(s)
• vehicle make, model, VIN/chassis number
• the vehicle’s kerb weight and maximum engine power
• details about the measuring system used to conduct the test,
for example, an engine dynamometer."
From what I've been able to find a stock 33 gts-t would have around 130ish kw/t if you're going off the factory engine and weight figures from nissan. That power to weight ratio wouldn't classify for an exemption however if you were to put the car on a weigh bridge and run it on a dyno it would most likely be under 125kw/t though. So I guess it's all up to which figures they take into account when doing the exemption.