On my 84 Rampage if I pump them up to 135 to 140 PSI it raises the rear almost 4 inches. When I put a 1/2 ton load in the back it is about 1 1/2 inch higher than stock shocks.
One day I picked up a 440 minus manifolds, a 5.9 Mag minus manifolds, a Chevy 350 minus manifolds and 1 head and 2 complete Chrysler 2.2 Turbo engines. With the air shocks pumped up at 135 PSI my Rampage sat level. Rode REAL nice too.