Use an oxy/acetylene torch on the springs while the car is sitting on the ground. DO NOT heat till the spring is glowing. Just heat it until the desired drop is accomplished. There is an episode of this technique on overhauling. This is not the propper way to lower but it's cheap. It's not as bad as cutting the springs but it affects the composition of the metal. Don't just heat one part of the spring either, heat a couple coils uniformly.