smaller turbo =faster spool but not as much top end power.
what you need to do is figure out what you want to make. you have stated repeatedly that you want 450+, a smaller turbo IS NOT GOING TO DO IT.
you need a VTEC head.
IMO instead of screwing around swapping turbos, for the 5th time. Listen to waht everyone has told you from day one, BUY A VTEC HEAD, make 500-550whp with the setup you have, and move on.
right now youll buy a 57trim, an still have the same problem. It will spool late, and not make any more power.
the HEAD is whats causing such a late spool, and such a shitty powerband.
eliminate the problem, the head, not make another one.