It depends on which Turbo kit you get. Hellion has a TT kit for gt500 costs about 7K. You can piggy back it on the stock supercharger and get up to 700rwhp or go straight to the motor and take off the supercharger and get up to 1200+RWHP on c16 gas and about 1000rwhp on pump gas. But you will need to upgrade some other things to handle that power like new driveshaft, larger heat exchanger, I would put a parallel intercooler (for track use) change the spark plugs, put on a boost a pump or larger fuel pump and so on which are added costs to the turbo.
---------- Post added at 11:39 AM ---------- Previous post was at 11:36 AM ----------
Also from what I've seen from the guys putting these systems on their cars 1000rwhp seems to be really close to the limits of a stock gt500 motor. Also it removes the cats so it is not street legal in every state.