A turbo can only produce it's rated power if you have the motor setup correctly to allow it first. When the below isn't accomplished, you break things. That is usually the start of many part-outs and sales.
1. All maintenance performed.
2. Any supporting mods for the turbo:
a. Larger injectors
b. Upgraded fuel system (pump, AFPR, lines?)
c. tuning capability (ECMLink, AEM, HalTech)
d. better flowing exhaust
e. upgraded intake (FMIC, hard pipes, SD)
You can google the rated power of the turbo, but everything above needs to be accomplished in order to achieve that power.
There is a ton of info on this board (look at some of the quality build threads on here. GSTwithPSI has a couple, "the_underdog"/Turbo Tom has a great thread plus he has Turbo Toms Garage on YouTube where goes through upgrades to both DSM's and his Galant.
All this being said, Yes, the turbo is an upgrade to your stock turbo, but it can't just be thrown on.