In order to run 20 psi on that turbo, you will have to have some sort of way to control your ignition timing advance, using 91-93 octane fuel. If you want to run 100+ octane fuel all the time, then don't worry about it It's def do-able, you just need all the parts that go along with it, to handle the power. And as the others have said, traction will be an issue. You will need damn good tires, a very strong clutchI(best clutch master's clutch you can get..500HP), and some form of a two stage boost controller. You dont want to run 20 psi in 1st, or even 2nd gear for that matter. You won't want to run 20 psi all the time either, you will eat up tires and gas like nothing. Having it available to run 20 psi is what you want. And yes, you will need good amounts of tuning(fuel and ignition timing). Sounds like the Megasquirt n'spark setup would be good for your objectives.

13.5 @108 MPH-2.2 60ft(stupid FWD!)
S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential
fuel injection)
My webpage: http://eclipsed4evr.home.comcast.net
-1998 Mitsubishi Eclipse RS-T- "Toy"
-1992 Plymouth Laser Turbo AWD(SOLD)
-2000 Honda CR-V(daily)