If i take out the back seat and the metal bar that runs behind it will it hurt anything?

 

the metal bar going behind it probably gives the car a little better balance in teh back, if you take it out it may make the rear start to roll more in turns,but I'm just guessing that so I can't tell you for sure

try it out; it's not gonna kill the car or make it flip over or anything like that so just test it and see =)