Anything less than 12"?
2006 F-250.
I like the idea of the air to keep the ability to tow, but have a better ride, but I don't like the Kelderman kit. Looks clunky to me. OUO never does much of anything less than 12".
Ideal situation, an air kit in the 4-10" adjustable range for 35-37" tires that allows for good towing capacity.