Tried that where I bought them. Only suggestion they said was re arching them or replacing them. I guess so they can sell me another set. Sticker on springs say made in Mexico so I guess that explains it. Stock replacements and been on the car 2 years and already sagging. They have no listings for add a leafs and I really don't want to remove them to have them put a ply in, so I guess I'll just live with it for now. I lost all options that don't require removal.
