The T3 series will build more than enough boost if you only want 300 ish HP.
There are other turbine A/Rs available, the one you list from VS comes with either a .48 or a .63.
Which are you basing your spoolup figures on?
I have a divided T3 housing that I have plans to run a diverter valve in to block half the housing at low speed. With the radius, w/ half the area equals half the AR, so 1.08 becomes 0.54. That assumes an exectly equal division, but should be very close.
I don't have a P/N or the aplication it came from (Flebay purcahse, I was building my own hybrid).
