I think 375ish crank will be the upper limit on a stock turbo. I know some tuners claim more but I am skeptical.
FWIW.....I plan to put down close
to 360-375 rwhp on a dyno jet with my mods once I get my e-85 mix on point.
n55 6 spd
jb4 map 5 ISO
ar 4 inch kittenless
Flex Fuel Wires
e30ish / 93
For sure well more than 375 crank.