right get underneath the car theres 2 mounts on your backbox if its standard one front one back and a silver heatshield above it make sure there not broken/loose if not then halfway down the car in the middle is your center box (big tube box) check the heat shield above that theres only one mount on that as far as i remember (il check to make sure in a bit) at the back facing towards the rear of the car, check its not stretched or broken as you will notice a strip of metal just below the end of the center box that they can sometimes knock against when moving