I've got airbags on my Mustang actually. The system I use is Airrex and it's been a phenomenal system to work with. I originally really wanted the system for car shows, but getting in and out of driveways, going over speed bumps are no longer an issue for me, and in that sense it's been so much more convenient where I wont have to worry about rubbing or scraping stuff off the car. It's a comfortable system, a lot better than a few coilover systems I've had in the past, but it's also rebound adjustable too on the shocks so you can really fine tune it with which PSI you're running. Best of all though, the Airrex system is an enclosed system already pre-built in a box so that you don't have to custom fabricate something and spend a boat load of money going with a custom fiberglass box or put wood paneling in there, you can simply install it, which is a lot quicker than other companies, get it on the car, and get running right away. A lot of these builds I find for air suspension can take 2-3 days to fabricate something, but Airrex will install in about 8 hours or so. Here's a picture of my car and the system that comes with when you purchase a whole kit (sorry for the dirty wheels, this was right after installing it):
