Thought about the EVO (201.035, 036) springs instead?
201-321-28-04 (front, short)
201-321-29-04 (front, tall)
The EVO rear springs are all for self-leveling, so that would only work if your car has SLS. Or how about 124 Sportline springs? Neil says those are stiffer than the 500E springs anyway... and they're designed for a lighter car, too.
