No down force in CM.

I keep thinking about front down force in my FF. I know it isn't legal in CM, but would it even help to get more grip from the front end of a CM car? If more front grip would be helpful, then might it work by putting some weight in the crush box(my car is way under legal weight anyway and 58% rear to 42% front) which is in front of the front axle? I am going to try it. Maybe someone who is a better engineer than I can say how much weight would be a good starting point and figure out if the extra weight would cause a momentum problem greater than the extra down force.
Mark