I bought my truck used, and it already had airbags, what brand of airbags I have never figured out. I recently bought an on board Air Lift compressor and gauge and installed it. It was kind of a complex installation, but was fun for me, as I enjoy that type of thing. The gauge with inflate and deflate buttons sits in a single gauge pod in the driver's side pillar (gauge pod was already on the truck), so that made for a clean installation.
The on board compressor is very handy, glad I got it. When running empty, I inflate the air bags to a minimal 5-7 lbs. After I hook up our TT, I pump them up a bit, as I find that softens the ride somewhat. When I drop the trailer, I deflate them again.
