Would depend on the setup, and how much boost you want to run. I think the turbo can flow 30+ pounds of boost, and definitely make in the upper 500's if you're willing to push it like that. I haven't had it back on the dyno for more tuning because I destroyed my diff last weekend, but 127MPH in the 1/4 at ~19PSI on pump gas speaks for itself.
Now, if you guys all want to tell Larry to put in a fuel system for free for me, I'll be happy to tell you how the 57 handles crazy boost.
Ced - What boost were you running on your 60 when you hit your highest of ~560RWHP? Were you pushing it hard or keeping it low? My car saw a TON more horsepower at 4400RPM with the boost at ~24PSI vs. ~17.5PSI (~445 vs. ~380RWHP, not to mention a gain of 75+RWTQ) before we aborted the run due to fuel issues.
There's little doubt in my mind that the 57 is capable of at least 540RWHP at 25PSI. And there's still got a lot of area to expand into, I'll spin that thing to 32+PSI if it can do it to see what will happen, if I ever do a fuel system (right before putting a 63 in, heh).
Driving a borrowed Civic when your Supra is dead sucks...
-Pete