There is no "best pressure" to spray at, only preferences.
If you want fine line ability and little overspray then use the lowest setting you can get away with. The 360 in gravity-feed mode will spray at 10 psi, but in siphon-feed mode it will probably need 18-20 psi.
The higher the pressure the better the atomization of the paint, but it also results in more overspray. Experiment and see what works best for you.
Mike
“Wisdom is the right use of knowledge. To know is not
to be wise. Many men know a great deal, and are all the greater fools
for it. There is no fool so great a fool as a knowing fool. But to know
how to use knowledge is to have wisdom. " Charles Spurgeon