if no gas, top up btw 10 to 20 dollar.
air con compressor spoil, v exp, i change b4, cost 800, but diff
car diff price, will be above 800, unless u can find second
hand.
bov cost around 300 to 500 dun no included install or not.
u driving wat car? tuning nid to use aftermarket ecu or piggyback.
which is quite exp, and must pay the tuner also.
famous & expensive 1, got hks sz, which cost 2.7k with tuning @
GR. or hks vpro @5k+ with tuning @ GR.
other wise, got many more choices =)