Does anyone know of a company doing progressive springs for the Velocity shocks? Specifically, I'm interested in a progressive wind for the rear track shock. Right now the only way I can get my sled to work as I want is to run very little sag out back which makes for a super heavy feeling front end. My idea is to run more sag with a progressive spring wind which should help prevent bottoming and resist excessive transfer at the point of sag. I see the Z-Bros option but it doesn't look progressive...anyone know of anything?