After recently installing Bilstein 5100s (set at 1.75") in the front, I started experiencing severe sagging in the rear when towing. After doing some research (on here of course ) I came to the conclusion that installing the Firestone Ride Rite Air Bag system would resolve this.
Installation took me over 4 hours (I'm not that technically inclined and have really shitty tools lol), but could easily be done in under 2 hours!
My rig: 2012 Tacoma Double Cab TRD Sport 4WD Short Bed (with rear TSB 4 leaf springs).
After filling both bags to about 20 psi, I was able to get an inch of added height (before: 22" from center of wheel cap to fender; after: 23").
I did notice a very slight/slow air leak on the driver side and will have to troubleshoot this further. More than likely, I'm thinking it's the air valve that screws in ontop of the air bags.
Surprisingly, driving around town (at 20 psi) I really didn't notice any decrease (i.e. stiffness) in ride quality; if anything it's about the same as it was before. Of course, I haven't loaded anything in the back of the truck nor towed with this setup yet. Will definitely be back to post my experience after towing, etc.