The payload on any of these trucks is determined by the weakest component, which is usually the drive train and the rear axle. So, changing the rear gear ratio will effect performance but not payload. Adding air bags will level the truck and give it a smoother ride but because of the added weight of the air bags will reduce not increase payload. All of the trucks can pull 16000#'s or more, but their payload can be as low as about 2500#'s particularly with 4-wheel drive, which adds about 350#'s (read reduces payload). Pay attention to your payload and estimated loaded pin weight. We probably know of a lot of people who exceed their truck's capacity and get away with it, but it is probably not a good idea.