I am lousy at getting good search results, to see whats been done.
That being said, here's some info and pics for removing and installing mesh
behind the lower air dam on XD GT's.

The RED squares show the position at the
back of the dam of push-to-release plastic extensions (retainers) of the dam, which hook over the
inside surface of the lower bumber.
There are 5 on the top inside, and 7 on the bottom inside.
The YELLOW squares show the position of a metal clip which fixes the dam to the bumber at the inside, or
back.
There are also a series of indents at the
front of the top and bottom of the dam, which are easily 'popped out' with fingers.
Method of removal:
(Remove licence plate for access)
1. A flat screwdriver can be used to push the two metal clips (YELLOW) rearward, and off the bumper and dam.
2. 'Pop' the top front indents, then push down on the 5 retainers (RED) at the top and back of the dam.
3. The dam will begin to be free itself, tilting forward with the top coming out first.
4. When the top is pulled out, the lower tangs or retainers will pull free easily, and the
dam is lifted forward and out. You may have to push the 7 lower retainers UP, but if the top is out, the bottom slides out easily.
Meshing around:

This is the lower air dam
I made inserts from a metal gutter screen, which is available at RONA
(Canadian Home Depot competitor).
The mesh is about 7~8" x 30" and two sections are needed to do the lower dam and front grille. Cost is $3.50 a piece or so.
I used 3 trimmed pieces, 1 piece for each section of lower dam, middle and two sides.

A side section. Edges of mesh overlap and wrap around the edge of dam.

Middle section, with mesh overlap, folded to conform to dam edge.
I cut out notches in the mesh where the plastic dam retainers protrude. The overlap of the folded mesh edge is about 3/8"~1/2". I had 4 metal clips which are pressure steel clips, and these are pushed over slots in the mesh, onto the dam, to retain the mesh in the middle. You can see these clips in the centre of each section.
The two slanted vertical strips of the dam between the middle and sides are wide enough to fold mesh into. Later, when this is installed, two strips of the bumper push into these grooves, holding the mesh firmly in place, as shown in this view from inside the bumper, after reinstallation of dam.

Reinstallation:
1. Front bottom of dam has 'tongues'. Fit these into the holes along the bottom front edge of bumper opening, keeping the dam tilted forwards.
2. Push the lower part of dam into the opening, and as it goes, tilt the top of dam into the opening also.
3. Start pushing from bottom to get the lower retainers in place, the work around the edges from the sides, and along the top. You will see and feel the retainers fitting into their places.
4. Finally, ensure the bottom and top FRONT indents are clicked into place.
Check for unseated retainers, which will look like bulges, and pop 'em in.
Note: I did not reuse the two stock metal clips. I think the dam is held in well enough by the retainers, and also by the licence plate.
You can cut a slot in the mesh if desired, to allow reuse of these two stock clips.
Hope this is useful.
Put your licence plate back on, and go out to strain dragonflies.
This post has been edited by 02CanGT: Jul 9 2006, 10:46 PM