Nothing worth sacraficing in the car that can be taken out for free in my opinion. In the hatch is a five pound weight, if you take it out it makes it alittle harder to close the hatch but its no big deal. Everything else that comes to mind besides the spare cost money to remove/replace. I plan to remove the antennae and rear wiper when I get my body work done but I doubt you want to leave gapping holes on the outside of your car. I would just save up for a turbo back exhaust, which weighs ALOT less then the stock exhaust (expecially those pre-cats) also get a UD pulley and lightened flywheel which are suprisingly very heavy in stock form, all those will reduce weight and add HP. Thats my take on weight cutting, if I wanted a lighter car I wouldn't have bought a Z.