Aside from stavros' comment weight saving wise remove everything you can unbolt i.e; rear seats, (seatbelts in the back are quite heavy items too), door trims, boot trims, lob the spare etc and then if you've no intention of putting the car back to original get the grinder and the hole saw out and chop stuff off - brackets etc. Also, all the soundeadening off the floor etc. Oh, get the headlining gone too.