You need to remember that faster moving air is a great source of down force. Its not as important to keep the air out from under our cars, as it is to smooth out the flow of said air. If the air thats moving under the car, can flow faster that the air on top, you can have down force. The way to use this to your advantage, is to make the underside of your car as free from bumps and protrusions as possible. If you can make the belly of your car flat and smooth, you will be well on your way to some good down force. Side skirts are there in real race cars to keep the airflow under the car from going out the side. In aftermarket body kit form, they are there to look good and make you think your going faster
Same for the front air splitter.
The problem with our cars, is the simple fact that they are airodynamic as bricks. We have lift in all the wrong places, and down force in oddball useless spots.
To counteract this, and to keep a legends or dwarf car planted, you need wings fore and aft. More so on the back end of the car for the added traction. 8* of pitch, and approx. 8" of height from the highest body panel with the rear wing, will gain your the most downforce to drag ratio. More pitch than that, the drag exceeds the benefit of DF.
