i have a 91 cummins and i bought a spring for it how much more power will i get and is it bad that my stock turbo makes 34lbs of boost

 

you won't see more power persay. You'll just see more useable rpms. Instead of governing out at 2700-2800 rpm you'll govern out at 3200 or so.

It's not really bad that your stock turbo is making 34 lbs of boost. Your truck is most definitely not stock to be making that kind of boost though. 34 lbs is what most guys will say is out of it's map range but (unless someone else wants to correct me on this) it isn't going to kill the turbo. I wouldn't push any more boost with it though. People say the stock turbo likes to be run in the mid to high 20s for boost. Above that and it's just pushing hot air.