My 33 has a 2.5" cat forward then after the cat it narrows down to about 1.8". Turbo exhausts are 2.5" from factory and GTR exhausts are 3" I think. If this is the case I've been thinking about swapping in a factory Turbo Exhaust.
Saw a black S3 33 GR today parked at Officeworks/Harvey Norman on Bell st. Also saw a really tidy Silver 34 GTR somewhere but can't remember where. Mighta been Doncaster or Rosanna road?
Decent looking chick driving a black NA 33 2 door past the cop shop in Heidelberg yesterday. Also saw a white 33 4 door with white wheels on Bell st, looked tidy.
I doubt they'd have a hand in actually stealing cars, they really don't give a shit about finding them though. No money in finding your car like there is fining your car.
Have you got one of them? They're just the caliper mounting bolts so they should probably be the same as the front. If you have any one of them you should be able to take them to a bolts and fasteners shop and they'll have something for you.