What a lot of ppl don't think about is that when you flash your lights, your taillights flash as well!!! So if your still within visible range of the popo, they can chase you and get right nasty.
I don't flash on the main highways [Hume, Princess, Pacific, Sturt, Calder etc] cos you'd have to be a first class unit to speed on them roads, cops, speed camera's and the Macquarie Bank reps are everywhere. I do flash when its on the back or byroads becasue you never ever expect radar on them. But I only flash when I'm out of sight/around the corner to the cops.
And I'm also a bit selective, motorbikes and trucks, normal cars are kewl, but high rollers and late model commodores/falcons [could be cop cars] are out.