Nismo rear bumper bracket??

simons

I was looking at the rear bumper on my 09 Nismo today, lying underneath the car and looking up at the exhaust and I noticed two black, metal brackets that looked like they should be attached to the bumper but were just hanging there.

Would someone mind looking under their car and tell me if theirs is the same way? There is one bracket held to the bumper with a pop rivet right behind the center of the exhaust and 2 black brackets. One on either side. Should they be attached to something?

There aren't any holes in my bumper for the other 2 black brackets to attach to at all. I'm wondering if they should be or if they just prevent the bumper from hitting the muffler.