Hey guys currently its set at 40lbs at idle with vaccume on and a 255lph pump. Do you guys think I should change it? I have full exhaust, with high flow cats, soon going to no cats.
39 with vac off you mean, take the little line off, the vaccume line and set it to 39 then put it back on? what do you mean with "the red and plugged"?
With the engine at warm idle, pull the vacuum line off the regulator; temporarily plug the vacuum line (piece of tape or your thumb); set the pressure at 38-39 psig; unplug the temporarily plugged vacuum line (remove the tape or remove your thumb); place the vacuum line back on the regulator. It will probably drop down to around 32-33 psig when you hook the vacuum line back up.
You have Electronic Fuel Injection. If more air is moving through the engine due to your mild mods, the injection system has more than enough capacity at stock pressure to automatically supply more fuel. Leave the fuel pressure alone.