Eibach Corporation
I had a set on one of my Turbo-t's and was not happy with the results. They are a very high quality manufacture.
They are a "variable" or "progressive" design.
Same kit that fits on an El Camino.
Being a progressive design, they did not seem to tighten up until you were slammed into a corner. Without any pressure against them other than the weight of the car, they seemed a little loose to me.
I think that Moog might have some springs that do the same thing, that may or may not be of the "variable" or "progressive"
design.