How do i tell if my low boost is because of the Sc outlet gasket
and what would be involved in changing it ?

Low boost is tyipcally not caused by the outlet gasket.

I would start with the tests for BCA and BCS
Boost Control Actuator (the metal can on the front of the supercharger) When you hit the throttle the rod should push all the way out.
Boost Control Soleniod (the electrical soleniod on the front of the BCA) you can unplug the hose from BCA to BCS and you should have full boost. It is bad to run like this too much. However good way to test the system.

While idling (which produced natural manifold vacuum) carefully spray carb cleaner around the base of the SC. If the idle changes pitch, you have found your leak.

To change it on a Series 2, you must remove:

Engine cover
Fuel Rail
Throttle cables
3 electrical connectors
several 10mm bolts
several vacuum connections.

You need a new gasket and two o-rings to replace it (if you find that you have a bad gasket which is RARE), and I also suggest replacing your fuel injector o-rings at the same time.

Or search on me for Replacing Intake Gaskets. Wasn't that long ago.

Edit.. http://www.bonnevilleclub.com/forum/...=intake+gasket