Installed an Up Down Air Air It Up system today and an ARB Dual Compressor
No more airing up/down individual tires anymore. System is really slick, turn your compressor on after initial install and set desired up pressure. Open the valve on the right to let air out of all 4 tires at once. Close valve after airing down and turn your compressor on and it will automatically air all 4 tires up the previously set PSI.
On my 37s from 30 psi to 14psi took 5 1/2 minutes. To go back up to 30 psi from 14psi took 9 minutes. That's for all 4 tires at once.