There are plastic ribbots that hold the plastic to the metal, like the piece above your radiator when you open the hood. Problem is, there are bars under the plastic on your bumper, that supports the strength of the front of the truck, in case of an accident. The metal is THICK and cannot drill through it, espically impossible if you try to get a nut on a screw to lock it in tight.
Long story short, the 20" bar fits the best on the bumper, but after mounting it with the included brackets, it will still only be held on by plastic. You will need to screw the plastic down with self tapping screws.
I know your probably just doing it for looks, because you mentioned that you wanted to join your friends in getting one, but dont cheap out if you want quality. I have a Rigid Industries 20" LED light bar, and it shoots out farther than anyone elses. The cheap $100 Chineese ones will get you looks, but the $500 Rigid will get you quality, and bragging rites for sure. Check out this YouTube link below buddy, it speaks for itself.