My luck ran out last Thursday night when we drove up to Newcastle to see the Pasha Bulka.
A massive defect station was set up and hundreds of cars were checked. (I won't be too cynical and say they were primarily checking the mod'd cars cause I'm guessing you would have already gathered that was the case).
I have a relatively stock car - exhust, wheels, enclosed pod etc.
One cop was genuinely helpful and explained the what and why- he said if I had an engineer sign off on my wheels & pod and paid the $700 odd for a track noise test then I would be left alone. I have now decided to take this course of action as I won't be stopped cruising and doing what I enjoy!
However, the other cop (W*nker) asked "Why do we (modders) need to change a perfectly good car" " Did I know the manufacturers put a lot of design into the cars" Blah, Blah Blah.
I asked him if he bought Levi's jeans or shopped at Target. He got the message, but unfortunately I think this kind of cop is the majority in the Highway Patrols.
All I can say is if you want to modify your car do it, but be prepared to pay for an engineers report and lets beat them at their own game!