I just bought a Porter-Cable (cheapie) GOOB sale, have not had the chance to play with it so what ever questions you ask help me out too!
Yes that would be the inlet pressure same as what my manual recommends
(Max 100) on mine
On reading some of the threads and some of the auto body sites these guns use a lot of air, a little 3hp compres not going to work.
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http://www.autobody101.com/forums/index.php
I like the "SHOW and TELL"