Posting this for a buddy of mine as he was asking what I thought. He has a '15 F350 CC,4x4, sb,6.7 srw, air bags and Lower Stable Loads and tows a 38' +/- TH. Truck weighs 8500 and TH at 15,500. Most ...
If he is getting overload spring slap, he has too much air in the bags. If reducing pressure causes too much sag, upper StableLoads would fix that. My F250 used both Torklift products to carry 4000 lbs without bags.