Improve the ride when towing and leveling out the truck. Have them installed on my truck and the last two.
My truck sags about 1 1/2 inches when loaded.
Inflated to 8# unloaded and 40 to 45# loaded.
The other item that helps is a good set of shocks - installed Bilsteins at 22,000 miles on my 2011. On my previous trucks I installed them after purchasing the truck - just did not like the ride of the OEMs.
Previous Duramax/Allison:
2005 Chevy Silverado 3500HD LT CCLB SRW 4X4
2004 GMC Sierra 2500HD SE ECLB 4X4