I added them to my truck and am very impressed with how they helped dampen the rear of the truck from bouncing around. I tow with a 1/2 ton so I am fairly close to the max load of the truck and was getting a bit of a bounce after having my trailer professionally adjusted. (tongue wait was reduced to around 525lbs from 700+lbs - it gave more range in my suspension) Adding the helper springs allows me to add air pressure prior to towing but lower the pressure for my daily commuting. I am impressed with them so far and wanted to pass along. I got them at Auto Anything for a little over $200. Cheap way to make your truck feel a lot better towing.
Here is the website to the company: Air Lift Company
Air pressure valves by the hitch
Helper springs installed
Here is the website to the company: Air Lift Company
Air pressure valves by the hitch
Helper springs installed