difference between MP vs SS 002's/003" springs

SS springs are designed, and optimized for 1/4 mile racing. They have a much stiffer front section, and more arch. They push the tires into the ground more, lifting the back of the car, upon launch. This creates oversteer. On a car that has to turn, the leafs should be close to flat, or at least a line drawn from the front spring eye to the center of the spring pack just under the axle should be level with the ground. The differential moves fore and aft when it moves up and down because the leaf spring moves in an arc. This actually turns the differential into a turn when it is set up properly. With too much arch, the rear could turn out of the turn, causing you to spin out. On our racecar, we set it up with a bit too much arch, which caused it to take turns very fast, like over 100mph, but if the track was slick, or we entered the turn too fast and had to slow down, we had what is called off throttle oversteer. That really sucks. Trust me, you don't want oversteer unless you are autocrossing and can get lots of practice.