Ultimately, it all depends on the direction you want to go with your car with regards to mass removal. As stated, Glanzas are reputed at around 920-940kg and the GT's at 850-870kg; with what NightSpriti's done, his car is already at 770kg fully wet. Similarly, my car started out at 960-1015kg (never verified initially), and is currently at 880kg, after removing out the interior, a/c system, PAS system, sound deadening, spare tyre & jack, bumper reinforcement, swapping on a lighter Front anti-roll bar (TRD unit is about half the weight of stock...a good 2.5kg removed), lighter wheels, much lighter seats and so on...no lightweight panels or windows...yet. I'm currently in the midst of having the ABS System removed too which should see a good few more kg's removed. The A/C system alone removes quite a bit of weight; I'd approximate around 15-20kg in total removed - this includes removing the A/C bracket (that's at least 1.5-2kg on its own!), A/C pump, A/C Condensor/Radiator and the lines...there's even the evaporator you could remove from inside the dash, I think that weighs 1.5kg or so as well?