I don't remember where I saw it, probably in one of the old Hot Rod/Car Craft/Street Rodder mags. They recommended using a pressure regulator that wasn't right at the gun. I believe it was because it was a disruption to air flow and by adjusting pressure before it entered the hose it had a chance to fill the hose with a less turbulent air supply at the gun. Yes there should be a pressure guage right at the gun though. Once the pressure is adjusted at the wall the guage at the gun will show if its correct. Seems logical to me that less turbulence as air enters the gun might be a good thing, but it might not make any real difference either. I always wondered about the ability of many HVLP guns to be adjusted properly when they use small orifice fittings. The whole idea is about volume of air at a lower pressure. I'm just looking to make the path of the air non-problematic by using larger fittings and trying to take the turbulence out of it. Might be overkill on my part, but I also don't see how it could have any detrimental effect when painting. Dick, I have my system set up so the tank pressure is 170lbs.The air goes thru a homemade chiller before going into the air tank. Piping from the tank goes thru a wall to another regulator/water trap and then continues as piping along the wall. That regulator inside the building is where I set my gun pressure. I know that it does no good to have the regulator/water separator close to or on the compressor, so I have taken steps to insure moisture gets removed prior to entering the compressor tank. Then after air enters the building I adjust the line pressure to suit the spray gun. My system is probably overkill, but the idea is to eliminate as many possible problems as I can .