1. You forgot an Intercooler.
2. The Garrett GT3571 is limited to less than 300hp at the flywheel. Way too small, unless you're planning to twin-turbo with two GT3571s.
3. The engine produces 219hp stock. We want to run enough turbo to provide 2x the power at 1 bar boost, even if the wastegate is set to 4-8 psi. At 1 bar, the adjusted power output is 440hp at the flywheel. At 10 hp/ lb/min of airflow, the engine needs an estimated 44 lb/min airflow from the turbocharger(s).

The cheapest twin-turbos would be rebuilt junkyard water-cooled T3-60 trims. (2), Mitsubishi TD06-20G, or IHI RHF55 or RHF6.

A good single turbo would be a ball-bearing Garrett GT35R or GT37. On the cheap side would be a Holset HX35 or HY35 (depending on your tune)

4. With the stock engine compression at 10:1, you're looking at 7psi on 93 octane pump gas ( 324 flywheel hp ). If you have access to 98 octane, go up to 11psi ( 385 flyhweel hp ). Access to 110+, go up to 1 bar ( 438 flywheel hp ).

5. I read recently in a tuning mag about someone running twin-turbos on an S54B32. This engine has 11.3:1 static compression and the guy runs it at 4psi with pump gas + methanol injection. He cranks it up to 8psi with 98+ octane + methanol injection.