Ed, I shoot base-clear and single stage acrylic enamel with mine and I use a 1.4 tip. I use 60 to 65 psi at the gun because it cuts down on the "orange peel". The smaller the tip, the less air pressure at the gun, The bigger the tip, the more air pressure. If you don't care about orange peel, use whatever you feel comfortable with. Please keep in mind that if you are using a gauge on the wall and not on the gun, you will lose 10 to 15 psi for every 50ft of hose. Also, if you have a "cheater valve" instead of a diaphram style regulator, pull the trigger back to the first stop to get a true reading on your gauge. Remember High Volume Low Pressure does not mean low inlet pressure. Sorry for the long winded post. Jim