i have a set of 450's for ya. they came out of a working j-spec vr4. cleaner than the 510's i replaced them with, lol, so cleaning wont be neccesary. i'm in darwin also.
i have a set of the twin squirt nozzle type from an rvr 450's, came out of a very low km jap engine, ment to be easier to tune and runs smoother ive been told.