The 5" strip of metal goes in the center of the spoiler for a solid mounting point. There are two screws/bolts on the car that it secures it to the underside of the lower center part of the front bumper/front facia. It is designed to fit between the cente of the chin spoiler and the front bumper/facia. You are supposed to drill through the chin spolier, the bracket and the front facia and use the supplied bolt, washers and nut. Then use the other six (3 each side) to secure it to the lower front bumper/facia. Hope this makes sense... Yeah...no instructions, but several guys here have put them on their 05' GTs (I have one but not installed yet) and this seems to be the way to install it. Colorado Stang installed his a few weeks ago, and we talked about the install. See his write up on the install.
Good luck!
Bill