After much debate, decided to go with a portable compressor to air up instead of installing on board air. Rested out today, from 32psi down to 20 = 10 minutes with ARB ez deflator then back up to 32 = 15 minutes with VIAIR 88P. Will get a little faster as I do it more, especially airing down!
PS - 10 minutes to air down from 32 to 20psi with the ARB EZ Inflator is really slow. Make sure you are unscrewing the stem out all the way. It takes <2 minutes for me to go from 42 to 18psi. When I first used the EZ Inflator I didn't screw it out all the way and it was slow like you are describing.
