this may not apply to you as your in QLD but in NSW the lowering law states that from August 1 2009 any vehicle that is lowered will have to carry a certificate stating that what they have done is aloud according to safety standard requirements.
you are not able to lower your car from factory height from more than 2 inches (5 cms)... and that if your car should be lowered you need an engineer's certficate to confirm it...

hope that helps a little bit