This topic has been covered several times. You will make more power with the Evo 9 turbo (up to ~420whp, depending on the dyno and supporting mods) than the Evo 8 turbos. The Evo 9 turbo will require an installation kit and will spool a little later. The Evo 8 turbos will get you into the mid to high 300s with the '05 turbo having slightly better top end due to the larger turbine housing; the '05 will also spool a little later for the same reason.
Obviously, your results will depend on the supporting mods, fuel, and tune.
And you can check out this thread for relevant 1/4 mile numbers with the stock turbo:
Top 20 Quickest/Fastest Stock Turbo Evo's 2009