I remember discussion about the one "left open" hard tube before somewhere.

I believe there is some support group for the PFC now that has software that tunes the PFC to your set-up. Has connectors to your laptop, so you can watch carefully what is going on.

I haven't bothered to hunt the software down yet, but my friend is very pleased with the results, after rebuilding his engine himself.

 

Best to plug those LIM holes when working. We dropped a UIM hold down nut down one of the tubes.

 

While not strictly vacuum diagram-related, wanted to confirm one more hose: is this the one that runs from the oil filler tube to the turbo inlet elbow?

From what I read, it appears the rubber hose on the oil filler nipple runs to one of the metal hard lines, then rubber again to the turbo inlet elbow nipple.

I am looking to add an oil catch can and wanted to plumb the outlet from the can to the stock location. i.e., insert the catch can in-line between the nipple on the oil filler neck and where it "returns" today. (My car is a '95 so no PCV.)

If the location shown in the photo below is correct, then silicone is a not a good material for this line, even though it doesn't carry an oil supply, the oil vapor (or if the can overflows and lets oil out its outlet) will degrade the silicone.