MM951

I used to get 5 bar on cold startup and down to 3bar at warm idle. Now the max I get is ~4bar and warm idle is still at 3bar. Oil is 20w-50, fresh, and filled to the line. It also has a new updated 1 piece oprv (86 block), rebuilt engine, and canton racing oil filter setup.

Should I let it be or look into this further?

KuHL 951

I might be wrong but didn't some people have some issues with the Canton set-up a few years ago? Your warm idle pressure is fine; I would leave it be unless it drops at idle.