I'm moving this to forced induction.....but I'll leave a shadow topic here.
I assume your boost gauge isn't metric (kpa), and shows -10 to 10? With zero straight up in the middle?
You need to be driving in gear and at wide open throttle to achieve higher boost. About 8-9 psi would be normal. Your supercharger was only used for 92 and 93 (and the 92 didn't have teflon-coated rotors, so you would be looking for a 93), but I don't think that'* your problem. They either work, or they don't.
I would assume your boost control solonoid or boost control actuator is bad. Or you have a vacuum leak.
Get a helper and do this:
1. Block the wheels (all 4).
2. Set the parking (emergency) brake.
3. Have your friend start the car, hold the brake firmly, and shift into Drive.
4. While holding the brake, have him/her rev the car to 4,000 rpms.
5. While this is happening, you need to watch the boost control actuator on the front of the supercharger, just to the left of the EGR inlet (do this from the side of the car, not in front!)
Does it actuate fully? Or only part way? Is the motion of the valve smooth and even? Do you hear or feel any vacuum leaks?
You may also want to try the boost bypass trick, and you can search for it here. There are many topics dedicated to it.