For the lockers (ARB, TJM, etc) you need about 90 psi (80-105 psi). In terms of volume not much, quite literally milliliters (has been said that a decent sized airline will hold enough volume for several actuations). In the TJM in the diagrams I gave above, the actuating cylinders are 1.5" long x 1/2" diameter, with a throw of about 1". Any sized tank is almost a pointless overkill.

CKSA 12 compressor:

Small, light, and designed for the job. Simply not worth stuffing around with anything else. 4.8" x 6.4" x 3.5", 5lb, 6.5amp flat out.

http://www.arb.com.au/air_compressors.php

http://www.arb.com.au/compressor_spec.pdf

2002 Sporty , Ironman 2.5" spring, 2" body, 15 x 7 ROH wheels, K&N, 15 x 10.5 Simex Centipedes, Powerchip 91.

"Never argue with an idiot. They will bring you down to their level then beat you with experience!"