is the car road registered???
then check with the RTA as im sure you cant remove the air bags and keep it registered...
the roof is about 20Kg??? and i know a lot of people have changed theirs.. but from what i have heard its a "give it to some one else" job
and takes about an afternoon...
like everyone else has said, remove everything from the boot, tyre, jack carpet, plastic linings and the metal plate infront of the fuel lines...
carpet in the car, passenger seat if you like, centre console (just leave the switch for the power windows)
dont remove the tow hooks if your going to the racetrack.. most track days and racing you need them to get through scrutineering.. so if you get boged they can tow you out.
other than that.. it strats to become permanant mods.. ie drilling holes...
but you can remove the plastic gards behind the front wheels etc...