After replacing my rear shocks with Bilstein HDs I notice the car takes on a bad case of rapid boucing in the rear. This only happens when on a poorly laid section of highway, but I would still like to find out the culprit. Could it be the softness of the front shocks along with the stiffness of the new rear shocks leading to a continual bounce when the road conditions are right? Anyone else experience this problem?

91' 300D 2.5