Is it appropriate to measure oil pressure at the feed of the turbo? I'm debugging what I think is a flow problem of some type...

 

Recommended range for journal bearing turbos?

I'm running an unrestricted 4an feed and burning hot side journal bearings. This is a bit of an odd concept to me because if I added a restrictor at the turbo, I'd measure more pressure. I assume the only way to test it properly is by volume or to measure pressure at the turbo itself, post inlet?