Spare, sound deadening, bodykit could all go... then some lite weight rims...
But depends what you're after... if you are after a racing shell... then the sky is the limit... but if you're wanting to keep back seats, ac, etc then I'm not sure what you want to acheive...
1st things first if u have a rear spoiler ..lose it, its just cosmetic and dead weight, they do nothhing for the car unless ur doing over 130 km/h (or is it 180??i dont remember) which if u value ur licence your not going to do anyway.
^^^^ lol.. a spare tyre.. ur car is 1400-1500kg, a wheel would be 5-10kgs... not worth the trouble at all.. cause if u get a flat, or even pop ur tyre when u take a roundabout too quickly or when u lose control when ur using that "power"..
lol.. 20kg then? i dunno, maybe i'm buffer than i thought haha.. all i'm saying its not much to the whole weight of the car lol.. cause yeh driving on a flat isn't fun..
Be careful what you remove as you need your seats in to be roadworthy, Also your spolier needs to be on if it has a high level brake light in it. or if you remove it you will have to put one in the rear window to be legal...
As far as the spolier goes that 1-3kgs you save will make a world of difference NOT!!!!!!!! The amount of time it would take to remove all the sound deadner for the benefits your get would not be worth it
Better to just save your coin up for the mods to help it go better..