My Cav GSi was converted from 4wd to 2wd by the previous owner. He used running gear from a J reg Calibra 16v to do this. With this in mind I went about lowering it and bought a Spax PSX kit with adjustable dampeners and springs good for a 60mm drop.
Now, the kit was for a 16v Calibra and was fitted without a problem by the place that I bought it from. However within a couple of weeks, the rear springs were totally flattened while the fronts were fine. I had the old Calibra springs put back in and everything is fine. The Spax rear springs were sent back and I got a new set about 3 months later, but I haven't bothered fitting them 'cos I don't know if the same thing will happen again!
I wouldn't have thought that the back end of a cav is much heavier than that of a calibra's, so if anyone has any ideas/solutions/explanations to give me I'd be eternally grateful!