I am certainly no expert, but from my reading I have gathered the following;
Fact is: The stock 87 compressor housing is more efficient than the stock HA compressor housing.
Most of the IC car owners have moved well beyond these discussions "What is the largest turbo available", since they have
plenty of options available for turbo's.
The HA crowd has limitations in the compressor housing available and unless you don't want to do too much machining/welding, the TA style turbo is about it
(If you are resilient and want to keep it Hot Air
)
The TA33 is good to low 12's (for sure)
Moving on .............
So, a TA33 that is larger on the turbine side of the equation, (while in this example no longer a TA33), will perform better at higher RPM, since the boost / back pressure ratio of is smaller.
Some of the experts stated that (at times), the benefit between turbo's (to a point) is not from the compressor side, but from the turbine side of the equation. Just look at the chart.
Turbocharger Compressor Wheels
What am I trying to say anyway?
I "think"
that a stock HA turbo with a larger turbine wheel/housing may provide higher HP output if it has the supporting mods.
If there "only" was a TA style turbo available that could put out 50-60lbs/min at PR of 2, we'd have a winner!! :biggrin: