Yes, it would be difficult to predict with accuracy what a 0-60 time would be.
However, you can estimate the horsepower:
E.g., 12 psi boost = .8 atmosphere of boost (note 1 atmosphere ~ 15 psi @ sea level)
There's also an approximate 35% adiabatic inefficiency with street drivable turbochargers, using intercoolers. Therefore:
.8 atmosphere of boost (from above) x .65 gain factor = .52 gain over stock HP. And since a stock S2K generates 237 flywheel HP, you'd be looking at ~ up to 360 HP with 12 lbs of turbo boost.
It seems reasonable that an S2000 could run in the mid 4's with this configuration. And indeed, there are other considerations...clutch, tires, road conditions, intake/exhaust, tuning, driving w or w/o VSA engaged, etc.