The fuel pressure regulator, the MAP sensor, and your boost gauge should all be hooked up to the vacuum port exiting the lower intake under the supercharger's snout. This is the only vacuum port on the 3800 SC engine that sees both vacuum and boost (unless you have a 96-97 3800 SC engine which also has a 2nd metal vacuum tree on the front of the supercharger - but later superchargers lacked this).
The plastic vacuum tree on the top of the supercharger as well as all vacuum ports on the side of the throttle body see vacuum only. DO NOT connect your MAP sensor or fuel pressure regulator to one of these.
OVERKILL IS UNDERRATED
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