Was it one of these?last melling i installed with .0025-.0027 main clearance and .0022-.0023 rod clearance, i saw about 10 psi increase at idle and up the RPM range. 15w40 oil and around 90* outside temp. never saw under 28psi at idle and hot after running it hard.
it will be hard to say the actual PSI increase you will see because most are building an engine at this point and clearances in mains/rods/ect can open up more for higher performance.
https://m.summitracing.com/search/y...y/duramax-diesel-v8?keyword=Melling Oil Pumps
This is the only one summit lists. Standard flow and pressure. Not sure if that's what I would want or not.