I didn't. It was trial and error. In my opinion, the A-body Hotchkis leaf springs are a little too soft for how much it lowers the car. I'm thinking about adding a cheapo helper spring on them to prevent them from sagging when my trunk has a bunch of stuff in it. God forbid right now I even think about fitting a spare tire in the back. Part of the problem has to do with the offset wheels I have, but still.