Fuel Pressure Requirements for 42lb Inj? 2002 Mustang GT

I have a supercharged 2002 4.6 that also has a SCT adjustable tune chip in it. It has GREEN TOP 42lb injectors and the car has been running great. about 2 weeks ago it started to give me a check engine light under heavy acceleration in the 2nd stage tune. I had it checked and the only code showing was in adequate fuel pressure. I had the pressure monitored at idle and while driving. It ranged from 40lbs at idle to as low as 37lbs when accelerating but no light showed while monitoring.

Can anyone tell me how much pressure should be available to feed these injectors? not enough fuel in a supercharged setup scares me. The company that Modified the car for the original owner used a Kenne Belle Boost-A-Pump and turned the factory pump speed up I believe but didn't add or change the original fuel pump. I have purchased a fuel filter and plan to change it as soon as I get a little help. Then have it re-monitored.

thanks for any help/info
James