I put an E8131 on a truck about a year ago, I have a 0-100 psi gauge at the seconday fuel filter, and the FDC is bypassed.
I'm seeing 30psi idle pressure and 60psi 2500rpm pressure, which is TM perfect.
I've encountered those that argue pressure doesn't matter, but 60 psi on a 3/8 line going to the head, could there really be a flow problem?
Truck is non-turbo M275A2, 500lbs lighter then a M35A2 and keeps up in the convoys I run in just fine. I have an EGT gauge and it'll pass 1200 degrees if I let it on hills.
Seems to me I'm getting enough flow.