You failed to say why you think you need them? Airbags will stiffen your suspension up some as well as level out your setup. I put Firestone on my 09, 2500 HD in an attempt to "firm up" the suspension. I'm pulling a 5th wheel and I was having some noticeable porpoising (up and down) I didn't like. I really didn't need it for the leveling aspect as my 2500 handled the trailer fine.
I went with Firestone riderite's (riderite.com) because of the ratings and ease of installation. Takes some time and if you are semi mechanically intelligent you can handle the install. A friend gave me a compressor to install on board to make adjustments on the fly but haven't had time to get that far. The bags and Rancho 5000 adjustable shocks have helped the ride a lot. Almost eliminated the porpoising. Only get it on nasty bridges and whoop te do roads.
Hope this helps.