unless this is a track car, and you plan on racing this all the time and getting the fastest possible time is a matter of puting food on the table, i dont suggest doing anything radical to lose weight. Dropping pounds off your car isnt going to be the miracle to make your car fast. Keep your seats, keep your spare, that way your not screwed if a tire goes flat. You dont have a fast car, you have a car thats probably in pretty good condition, dont ruin that and start ripping it apart.