Depends on who pulls you over in Melbourne to if it's traffic cops they are not easy to get anything past as they will go right over everything! But really if you are not silly and the car is not overly modded then they shouldn't pick on you!
It's only when your car makes noise ie 3inch straight out exhaust or big pshhh out of a bov, or doof doof, or chirp chrip as turning and your with in roadworthy standeds then they shouldn't be able to find anything wrong!!
BUT they do make rules up as they go! ie I can get a roady with front mount cooler and properly fitted pod but if I get pulled over the cops go you can't have both it one or the other what can you say!!
That's my thoughts anyways