The last few months I had started noticing a VERY loud and annoying rattle that I had to find a fix for. My amazingly brave girlfriend opened the door on the passenger side and grabbed the sideskirt to stabilize it and the noise was much quieter. So, I figured out that the sideskirts were causing the rattle. I got under the car and rattled the sideskirts and noticed that the stock clips had gotten so loose that they were practically worthless. For people with cars as low as mine, rocks, pine cones, cans, railroad ties, and whatever else will smack the sideskirts and cause those plastic clips to loosen or break. So...I decided to fix it and come up with a much more durable and tight way to fasten the sideskirts. I figured I would post up a tiny writeup of what I did. Please add orig.jpg to the images to get huge pics.
Instead of buying new clips I decided use a "Nutsert" which is a metal cylinder that is threaded on one end. Here it is compared to the regular clip:

To use the nutsert you thread it onto a gun that is used like a pop-rivet gun if you've ever seen/used one. The gun looks like this:

Nutserts work by pushing one end of the nutsert in a hole and then squeezing the gun. As you squeeze the gun the nutsert compresses onto itself and the end in the hole flares to ensure a tight hold. You turn the knob on the gun to remove it and you're left with a metal insert that is threaded. There you have it, a strong, metal threaded insert that you can be sure won't move and will hold a metal bolt.
Now that we've got that little tutorial out of the way we can get to the small matter of what I did to fasten it.
As anyone who installed their own OEM kit knows, the sideskirt fastened with plastic clips that go through a bracket and into a hole in the frame. Well, since we already have a hold in the frame, let's get a nutsert in there. I used a 1/4" nutsert and I had to increase the diameter of the hole in the frame by about 1/8" to get the nutsert in. After you've inserted your nutserts you just need to punch a hole in some pieces of rubber to serve as a dampening between the bracket and the underbody. Here are some pics:

Now you just need to throw your 1/4" bolts in nice and tight and admire your work.

My sideskirts are so solid and tight now. I can't believe I never did this before. I don't know if you guys want or need to do this but I figured I'd throw it up here anyway.