Just to clarify a few things regarding odometer tampering again...
1) Odometers can be wound back at many points in the importing process, often even before they reach auction. Don't always assume that the current owner/importer/dealer selling the car is responsible for it, or knew it had happened when they purchased the car.
2) Odometer tampering has been reduced massively by the Japanese govt listing kms every time a car is re-registered. This appears on the export certificate that accompanies every car that legitimately leaves the country, a copy of which is kept by the compliance workshop. If in doubt with the kms, ask to see the export certificate.
3) There ARE genuinely low-km cars going through auctions, but you have to pay HUGE money for them, often more than what they fetch in Australia. I had a guy a couple of weeks ago who wanted a mint Evo 7 with under 40,000km on it, and I told him he'd need to spend $30K, even though you can get (admitted higher km) examples here in Oz. We got him a car a touch under that, but even still, you have to pay if you want top notch.
4) Many Japanese owners are now starting to provide documentation to support the kms travelled when gauges are changed, as they become more savvy about what exporters are looking for. My car, for example, had a genuine 24,000km and the owner listed exactly when and how many kms the car had done when the Nismo gauges where put in (along with a few other Nismo parts lol). I have all the receipts to verify it.
One last piece of advice - when choosing between a car with big mods/horsepower and high kms, and a near standard lower km example of a car, choose the latter. This is especially the case for GT-Rs.