I installed (about 2004) Firestone air bags on my previous truck, with individual manual in cab air filler valves. I suggest not using one filler for both bags. I will explain why if ask. Easy to check psi, air up or down and out of the wind, rain or sun. The bags required 5 psi minimum. I used a cigarette lighter powered compressor for air. This worked very well.
In about 2008, I bought an Air Lift incab controller. I also installed it my self. I just "T"ed into what I previously installed. This worked great. I developed a slow air leak at a fitting on one bag, and about every hour the controller would add the necessary air with no input from me. I still had the option of using the in cab manual fillers if the controller failed.
Last year, I purchased a 2004 Dodge 3500 DRW. I installed the Ail Lift bags wit h built in bump stops. They require no minimum psi. I Moved the Air Lift Controller from my '96 truck to my 2004. I also did the air lines separate for each bag, and installed manual fillers in the cab below and to the left of the steering column.
On the '96 I mounted the compressor under the hood, and the control module under the center of the seat. On the '04, I mounted everything under the hood. On both, the controller itself was mounted on the dash.
I have been running my controller for about 13 years, thousands of miles and on two different trucks. It or the bags (Firestone or Air Lift) have ever given me any problems. Two leaking air fittings, and one melted line on the exhaust is all.
As you can see by this post, I have mixed parts between the manufactures. Air Lift no longer markets the digital controller I have. I will say, even though it is backlit, I find it hard to see the numbers. They are too small and not well lit. Hopefully the new ones are better. I am sure I have given you more than you have ask for, but hopefully I have given you some thoughts.
Wayne