Better shape to the air dam
 

I've just put on a cardboard template on red, 91 civic. Wouldn't it be better to have the bottom edge leading aft? Or is the object to divert air from the bumpy undercarriage. The dam looks very un-aerodynamic. I know ideally pointy front/smooth undercarriage, but having not been very successful finding the 4x8 abs I want (hint, hint, source please) I not quite to the undercarriage.

The purpose is to not have as much drag from the components hanging down. If you had a smooth flat bottom you might actually want to direct air under