The plastic bits should stay on with your old exisiting bumper i think. You get foam ones with the 172 bumper, if you dont have any with the 172 bumper it shouldnt matter too much i dont think? Correct me if im wrong though. If you dont have any foam bits with the 172 bumper drop me a PM i think i have a spare set somewhere. Wayne
Edit - Also have you left your non sport arch liners on? If so they wont work with the 172 bumper
The white bits you mean? I need some foams ones, will pm you, thanks dude.