audi made 450bhp in the RS6 turbochangred with a 9.3:1 compression and silly low boost like 7psi IIRC (had a little overboost which may make the top figure)

I suspect even the standard engine on 10:1 would swallow 4-5 psi quite happily and make damn good power!

for my money

lexus is200, lexus 1ufze, 2 turbos, misc