Fuel pressure question
 

Just finished a hair pulling job on putting in a new input shaft in after the stock one broke and a piece of it was stuck in the clutch not allowing it to disengage after the install. Had to drop transmission multiple times but now thats all fixed.

Put on a fuel pressure guage while it was in the shop and pressures seem to be good under no load (26 idle and 38-40 @2500 rpms) but when under load at WOT out on the road it drops to the teens. Lowest I saw was about 12 or 13. Is this no good? What should it be at?

Currently this is how the truck is set up: 100 plate FF, star wheel adjusted, rack plug, 181DV's, 4gsk, injectors are said to be 60hp over stock, BHAF, 5" exhaust, stock turbo, 5 speed with the 175hp pump

Its not the best for it, I like 40 to 50 psi @ WOT