14-17 is way too low. Should be around 18-22 in-hg
Best to use the vacuum lines off the throttle body or tee into where the MAP sensor vacuum lines are at the Upper Intake Manifold which obviously is the supercharger. Under the snout area.
BTW - An exhaust system leak close to the front pre-CAT 02 sensor can cause a P0171 DTC to set.