Gotta concur with the others on this one...you will really like the "bags". Firms up the rear end (that didn't sound right!
) when towing the Monty.
Experiment a bit to find the right pressure for YOUR truck and trailer combo...for mine I inflate to about 40 psi UNLOADED and then with the trailer on it, the pressure typically goes to about 60 psi.
I don't drive with 40 psi unloaded for long though! Like everyone else, I drop to 5-10 for normal driving.
With the rear springs I have (not stock) and the air bags, I feel I get the best of both loaded and unloaded performance.