I'm surprised that no one has pointed out the obvious -- that if you are actually hitting the bump stop, at that point you are driving a coal cart with zero suspension. Even F1 cars, running enormous downforce, have some suspension compliance. On a geometrically smooth plane of asphalt, you might not need any compliance, but in any real-world situation, including autocross and race tracks, you have to have something, or you wind up bouncing wheels off the ground. Not only do airborne tires have zero grip, the instant transition from full contact patch to zip tends to really mess up your line. A little rubber or poly in there to soften the transition is a good idea.
