Vacuum gauge...

[The Green GT]

What line do I need to splice into and where is it?

 

[FlyBy763]

Any vacuum line under the hood that goes to the intake more or less. I used the one going to the fuel pressure regulator. You should be able to tap into one on the vacuum tree right by the drivers strut tower.

 

[HISSIN50]

The FPR line isnt ideal. You can actually affect the fuel pressure - it's best to let the FPR remain a dedicated line.