You now need to remove the pair of nuts/bolts on each apron.
Removed
Now you should be able to slide the diffuser under the aprons. This isn't the easiest task since it puts a lot of stress on the 3M tape holding on the aprons. Mine ended up coming off partially. There is a problem though. You may be able to tell from the photos below, but because the diffuser does not conform to the shape of the bumper like the apron does, there is a point on the apron that pushes against the diffuser that makes it stick out unevenly. You can shave this off, or just live with it. If you leave it, it will more then likely scratch up the area that it contacts.
Now you can line up the holes from the apron and diffuser and bolt them down. I opted not to use the ones I pulled off and used longer ones since it makes the task MUCH easier. I recommend picking up a hardware kit like this one I got form Advance Auto.
Here's a better photo of the piece you probably want to shave down.
