As some of you know, I run the Flex-a-Form fiberglass leafs... mono-design, lightweight (approx 10 pounds each)... I discussed with Flex-a-Form my desires and intentions (SCCA autocrossing... national-level competition, class E/SP)... they wanted the 4-corner weights of the car particularly as I'd be driving/competing. From that figure, they recommended 225 pounds per inch, with a 5" in free arch (uncompressed)... settled at about 1-1/2" arch (compressed, but later settled flatter after a few months. Poly front/rear bushings. If I'd do it again, I would go slightly stiffer (~250 with a 4" arch, which would still settle close to flat after a while. The fiberglass leafs are supposed to give quicker response/reaction. I've been pleased... have run these on the car since mid-late 1980s.

Keep in mind, that I also run 1.24" diameter torsion bars (rated at 425 pounds per inch... after trying several smaller TBs), and I have adjustable Koni shocks, and the car's main intention is competition autocrossing (pylon and hi-speed tracks)... and its still comfortble on the highway cruising (avoiding streets with rough surfaces).