So, I'm wondering what ever happened on this question. I have an 01 3500 with a 3rd iteration of the factory pump mounted on the frame. I have a fuel pressure gauge and it reads 13.5 psi at the VP-44fuel inlet. Doesn't seem to vary at all no load to going up a grade with my 30' toyhauler behind. I drive pretty conservatively, keep the EGT below 1200 always, usually below 1150 for most climbs. Seems reasonably prudent to ensure long engine and driveline life.
I guess I'll have to update my files. Haven't been here in quite awhile. Lost a house and then took care of my dad with Alzheimers for 2 years. Now, new state, new house, new outlook.