Re: Custom Springs
Rather than trying to adjust ride height (in 10mm increments) have you considered adjustable spring seats that allow for a multitude of height adjustments.
I know there available for Falcons (if that's what you've got) from people like K-Mac, Pedders and Bilstein just to name a few. Either with a snap-in circlip type arrangement with about 5 selectable heights or a fully threaded collar.
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