One cheap way is to paint most all jagged edge parts gloss black, especially the big K-member. Gloss paints are more slippery in the air compared to the stock look of matte/satin finishes of the day.
Dams can be constructed as said and serve two purposes for speed and safety. I've been planning on creating one out of aluminum sheet to be detachable or reinstall able at any time at the track for a street/strip setup.