i have a 6hp 30 gallon craftsman compressor and it kepped up verry well with no spitting and set to 40 psi with a water seperator and i use the 50.00 hvlp gun from eastwood 2 of them 1 for color and 1 for clear.

the 2.5 i think would stay on all the time because i wont fill the tank fast enough while painting it takes me 5 min for 1 coat to lay down and the compressor kicks on once

i had one fan blowing out of a window and the grage door open a foot then when i was done spraying i would open the door and let all the overspray linger out.