Another reason why some people feel they have too much truck rear end sag is that their WDH is undersized for the tongue weight of the trailer. They tilt the hitch head down all the way and hook up the chains and tighten them, etc but the back is still down (and usually the front is still up) and their bars look like the letter "U". If this is the case, you should actually get an appropriately sized WDH or alternatively use air bags to lift the back up a little (as long as you do not exceed the rear axle weight). In this example, the WDH bears some of the load and the airbags "sort of" bear some of the load.
