I couldn't get my Simons Sport system to fit right and neither could my full-time mechanic neighbor (it banged into the floor pan much too often). I finally took it to a muffler shop with an excellent reputation. I should have taken it to the experts in the beginning. BTW, the back hanger is indeed hung by the bumper bracket but the muffler shop put a better hanger there than what was included in the box).

Since then, no banging, more power and better fuel economy (I also switched to the dual downpipe).

It sounds distinctive and looks quite nice too.