Took me ages to find stuff too but my comments only relate to turbine or hot side as the compressor doesn't have as much of an impact.

I had expected that 0.64 a/r would be about 8 cm2. Kind of pleased that it is bigger. Stops me having Blouch envy!! The proof will be when I fire up the engine in a few weeks time.

A friend has a very similar sized turbo in many ways but with a 8cm or 0.55 AR. Apart from the differences in his build we may get to see some of the characteristics of the smaller turbine housing when get gets that running too around the same time as mine. Won't be directly comparable as too many engine parts are also different.