Because I used a polycarbonate material, it is VERY strong (also quite expensive). To get it thicker would raise the weight considerably and get very expensive.

The way to make it appear thicker is to use injection molding then it could essentially be thin but have a hollowed out area to make the actual material thin. $10K plus for the mold so that is out. BTW the OEM diffusers use this method. And did I mention that you would need two molds because right and left mirror each other.

By using a solid polycarbonate it is solid, strong and can be essentially made to fit right or left. I do want to round the edges more. I can do a completely rounded edge or tapered to each side. The later would then require specific right and left and would add a little to the cost.

They are actually much larger than they appear. You don't see the extended piece under the far right and left. They follow the edge of the bumper skirt. I tried this method so I could use the existing screw mounts on the standard bumper skin. Two using the existing screw holes and one addition self tapping more to the inside. To attach to the fins on each side of the exhaust pipes, I used self tapping screws to secure that edge from underneath. With the turbulent airflow coming under the car simply using tape will not hold up.

I have had them on a month and they are as tight as when first installed. I have done some continuous high speed runs on trips as far as 120 miles with no problems.

I was concerned that they may cause lift but it appears if anything there is additional down force. The car remains very stable at speed.

Last note...I am thinking of offering them with a matte black finish. To apply the synthetic CF finish would be very expensive if I apply it to both top and bottom, also I will probably only apply it to the exposed area. I am trying to figure a way to shorten it yet secure it as strongly as it is now.

It looks MUCH better than without anything, and also looks good in conjunction with the OEM diffuser.