That is my current concern as well. My car is at Muscle Motors right now having the GTX exhaust put on. Since we have to remove the bumper, clamshell, etc. to install the exhaust, we are looking into options for leaving the bumper off. No question, the car looks better without the bumper, just how important is the rear bumper in lateral stress loads to the frame is the question. Maybe not much, but would sure hate to find out in a year that the rear body panels are rubbing together or causing some other mess with the clamshell.