There really is nothing to them... The ground control kit uses a 2.25" ID linear rate racing spring.. They happen to be made my Eibach but any brand with the same specs would work just as well... Race parts outlets sell coilover springs in all lenghts and rates for around 50$ apiece, Eibach or not.
One thing for sure, there's no using your H&R or anything else on them!! Gotta have the perches to manage the 2.25" ID springs.
