Is it possible to tune water flow in a parallel loop to suit different restrictions?

[Waterlogged]

You would want a flow meter on each branch, not a pressure if you really wanted to tune. Normally flow in each parallel branch will adjust until pressure is equal in each line (Lower restriction branch increases flow until pressure drop of that line is equal to that of the higher restriction line, etc.)

I wouldn't put the CPU in parallel though, I'd leave that in series up front then split out.

Thanks for the correction Martin.