https://youtu.be/IyRaz1q9HEM?si=2rHo0JRBmSYA8j72
This video is after replacing FPR.
Before I replaced it the pressure bounced with every injector pulse on the order of a psi.
Had very simulator errors suggesting vacuum leak. The thing is: e53 doesn't know the fuel pressure it does the matu assuming 50.0 psi and any time it isn't, it will send less or more fuel.
In the video above I was wot rev and it would pull the psi down like 1.5 psi but at idle it was rock steady.
I thought I took a measurement of the small o-ring but that was the only problem. Gas under pressure was getting past and throwing off the regulation.