Just bought a very nice '93 940 turbo sedan today. 70,000 miles, original owner. The car drives very smoothly, handles/brakes well. The only problem - no boost. Under the hood looks great, no leaks, no immediately apparent vacuum problems. With the car idling, I put my hand behind the exhaust (which in this case is the axle pipe, since there's no rear muffler!), and there was little to no exhaust output. With my other turbo, even at idle, there is a healthy amount.

Also, when driving, car is a little sluggish, and there is a very prominent hissing sound coming from the cat/resonator area, which increases with throttle.

I'm assuming this is due to a plugged cat, right? Hopefully not a seized turbo! The exhaust system is extremely quiet, even without the rear muffler.

If the turbo were seized, would the symptoms be similar? Since the car has so few miles and has been well-maintained, I felt I had to take the gamble with this one!