I am planning on hooking mine into the intake manifold, possibly the vacuum tree on the firewall. That way you are actually measuring the boost in the intake. I think any of the vacuum ports under the back of the intake would work.
My paxton intake elbow has a spot to hook up a boost gauge, but if I put it there, it will show me the boost the SC is making all the time even if the throttle's not open much. I want to see the actual boost going into the engine.
Of course I've been too lazy to drill a hole in my firewall to run the tube to the gauge yet, so it's still sitting in my garage.
Jeff