Stock pump and stock regulator should retain what fuel pressure at idle and at WOT?

 

idle i think is 43 psi. i dont rember what wot pressure was

 

Fuel pressure at WOT with the engine under load shouldn't drop more than a couple of PSI from what it is at idle when the vacuum line is disconnected. At idle it can be between 41-47 PSI, no vacuum on the regulator. For instance, mine was 42 PSI from the factory.

 

At idle, pull the vacuum line off the FPR and plug the end of it. Ideal pressure is 43.5psi. GM accepts anything from 41-47psi. Reconnect the vacuum line, pressure should drop proportional to intake manifold vacuum. 6-8psi drop with a stock cam is usual. Less drop with a bigger cam.

Tape the gauge to the windshield, take it out on the road, up to max load/max RPM and the fuel pressure should not drop below 40psi, and as noted in the post immediately above, should drop no more than 2psi below what you measured at idle with no vacuum.