Well usually it isn't the turbo that is no good. I know the vacuum system which controls the turbo is usually whats wrong. Just test the vacuum system at the waste gate, boost solenoid and vacuum pump itself. If they aren't working, you can make a mechanical waste gate called a turbomaster and there are plenty of threads on how to make one yourself.

As for getting a new turbo, I wouldn't waste $700 on buying another GM-series turbo. Probably just wait till you can find a hx40wII turbo and put that on, its a pretty popular swap as well, I think all you have to do is play around with the down pipe the rest is pretty simple, but I don't really know.

But my guess is that your vac system isn't working right and all you really need is to find where the problem is. Tons of people go with the mechanical waste gate, but usually suffer worse mileage, but most of them think its worth it.

 

Is it just me or does it seem like he isn't even reading your posts?