this is a great thread for sure!
So far I have removed everything from the back from my ZX5 SVT. I weighed everything too and these were the numbers I got
Rear seats= 66 Lbs
Rear Sub box = 15 Lbs
Spare Tire/ Jack = 35 Lbs
plus all the lining, bolts etc added another 15 Lbs.
So without even doing much work that already drops 131 Lbs. I dont plan on getting TOO crazy with it but another good weight reducer are the wheels. I dont know how someone in this thread said they stock SVT wheels weigh 13 Lbs but They actually weigh close to 25 Lbs each. I will be going with a set of 16" Rota Slipstreams which weigh 14 lbs each. That will shave off another 44 Lbs of Rotational unsprung weight which is pretty big.
Add a lightweight battery and possibly a CF hood all this would add up to about 220 lbs are so.