Its no biggie.. you just take it to an approved tester.. give them 15 minutes and they'll do the required test and tell you want it read at and whether you pass or fail. If you "fail" you just get whatever modified and come back and try again.
1. Its a b.s. law and just comes from the officers "thoughts" of whether it is actually too loud or not. As he doesn't use any meter he just makes it up on the spot.
2. Its perfectly possible to pass with an aftermarket exhaust.. I passed at 89db with a full dump system, highflow cat and Super Dragger II catback. Most won't though, true.
3. Its 3/4 of the max rev range, so around 5200rpm for an R33
4. You don't have to send it to the EPA, just take it a testing station, and they forward it on when it passes and its all done. The test is around $30
5. Here is the list of testers.. just rock up to one http://www.epa.vic.gov.au/Noise/testers.asp
6. Please do a search in future, all this has been coverd COUNTLESS times as most people have been there one time or another