Been down here for 7 years now with 3 cars rego'd in QLD. They can send you to get a EPA test done and can issue you a defect. only thing is, RTA doesnt tie in with TMR systems so the defect can't be logged against your rego. the NSW cops seem to have a lot of trouble accessing QLD rego info from their cars so you'll need the rego receipt your sticker came on to prove rego too them. (happened to me twice so far).
Outside of that, they generally CBF'd pulling us over in the long run.