the rules (if i have them correct) in quensland are that as long as the wheels are covered, as in there tyre does not protrude from the body, then it is legal (with the gaurds being part of the body). you would attract alot of attention with that colour though so i wouldnt count on it, the cops would do you for something..because they can.
also the GT42R turbo's specs may be misleading, 1000hp is the figure that it is capable of flowing (its usually give or take about 100-150hp of that figure), so it doesnt nessesarily mean when you bolt it on it will give you 1000hp, although it would be handy.
having said that I'm not aware of any 3s's that have gotten that sort of figure? (maybe i need to get out more?) i suppose it possible though.