Ya know, I might be wrong about the 3/16" part. From what Doug over at Precision mentioned on the phone was that he does not use the high pressure springs, he uses shims with the stock spring to bring the pressure up. I'm sure he has his reasons of doing it that way. I am
certain he does a flow/pressure test.
I have a HV pump on the engine right now. Haven't done anything else to it, no HP springs, no shims. Stock out of the box Melling HV pump from Napa.
We'll find out in a little while how it acts with the new pump. I have to change out a leaking rear main seal, so while I'm there I'll try out his pump, not gonna hurt any.
Take a look.
Precision Oil Pumps