Certainly the engine in question will make a big difference in the outcome (e.g. being DOHC with much better flowing heads, the LQ1 responds significantly better to boost than the 3800). However, even with the 3800, a turbo will do much better than 400whp with 10+psi.
https://www.youtube.com/watch?v=y-fabcSsh8s
434hp/400trq @13psi with filter, 446hp/403trq @13psi no filter, 511hp/446trq @16psi, 529hp/472trq @17psi
https://www.youtube.com/watch?v=a7qrYOW1HgU
584hp @19psi
https://www.youtube.com/watch?v=SnOhrsz2OWg
593/whp @psi unknown
https://www.youtube.com/watch?v=-fE0IvDuFfk
606whp/628tq @24psi