I don't think there are a lot of R51 guys around here at the moment. I guess it would depend on how much body lift the R51s need for popular tire fitments. Seems like you could make the 1.5" kit, but make it stackable, so a customer could order one kit and be at the limit of lift without further mods, or two and jack it way up if that's what they're after. I assume either option would require different bolts, though, so maybe that wouldn't work as well as I'm thinking.