My turbocharger candidate list is still open while I try and find an upgrade that fits what I am looking for.  A potential contender is a revised FrankenTurbo F21 that Frankenturbo released some early prototype photos of.

A revised, billet, compressor wheel:

and even more interesting, a mixed flow turbine:

This looks to be an excellent combination for trying to maximize power on a stock motor while retaining good spool up characteristics.

Time will tell if the prototype lives up to the design goals.