Hello,
I did a silly thing and didn't label my vacuum lines when I removed them while installing a new secondary rail. Now I have two hardlines which I'm not sure how to connect them.
The two lines exist near the three secondary turbo lines(One has a line on them but they are two hard lines next to each other). Are they the check valves line? Is the one closer to the fuel line the blue line.

In addition, what is the line that has the arrow pointing towards it? It's in between the rat's nest box and the secondary fuel line.

 

No answer so I’ll jump in. You might have solved it already

The two hard lines connect with a U-shaped hose.

Yes, the two hard lines being joined are different diameters.

Going to the diagram, they are part of the circuit formed by the grey lines denoted as "vacuum, pre turbo". It is not really vacuum just slightly below ambient pressure by the pressure loss in the air inlet ducting and air filter. It is piped and hosed from the turbo inlet to a distribution manifold. From there two lines go to the turbo pre control and wastegate solenoid valves. The other goes to the oil injectors. Your arrowed hose is the B-B hose which tees off to the oil injectors.

There are no check valves or orifices in the grey lines.