Tell us more, Irishdrum. What sort of improvement are you looking for? Or maybe I should say, what problem are you trying to fix?
Also, are you talking about air-adjustable shocks or air bag helper springs? They have different purpose and effect.
Neither one will increase your GVWR or GCWR. Air shocks can change the ride somewhat. Air springsmay have some effect on rear end wallowing or sway, though they would not be my first choice to try to fix that sort of problem.