The Aeromotive regulators are just about bulletproof...there will RARELY be a problem with those. The most common cause of high pressures will be a blockage on the return side of the system (post regulator) or a gauge problem. We've seen issues with the factory in-tank hardware causing increases in pressure at the regulator because of the restriction it places on the system.
FWIW...some people have complained about odd readings from Liquid Filled gauges. This has to do with the internal pressure of the gauge changing due to the LF gauge being sealed. Temperature changes will change the internal pressure of the gauge, which is the "Reference Pressure" that the gauge uses. 0psi on the gauge means that the pressure on the inlet of the gauge and the "Reference Pressure" are the same. 50psi means that the inlet pressure is 50psi higher than the "Reference Pressure". If the temperature of the gauge causes the internal "Reference Pressure" to rise by 5psi, and the inlet pressure stays the same, the indicator on the dial will show 5psi lower. BTW...I was just throwing out a number, I don't honestly know how much the "Reference Pressure" changes. All that said, LF gauges seem to be the only ones that will survive when permanently installed on a PSD engine. Non LF gauges will be more accurate and won't fluctuate with temperature, but we have not found one that reliably survives the vibration.