My take is Higher compression engines are:
-more thermally efficient, less heat out the exhaust (lower EGTs) which spools the turbo slightly slower. BSFC improves.
-better off boost due to torque improvements
-won't eat as much boost (dynamic compression) as low compression engines do.
on a large engine with a small turbo (8374 on a 3.2 is a small turbo in my mind) it makes sense as you won't get much boost into the motor anyway before you overspeed the thing. I just hit the speed limit of an 8374 on a 2.6 at 8000rpm and 27psi at 490kw. so a 3.2 with the same VE% at around 6300 rpm you'll have the same boost limit. if you rev any higher you'll either have to taper it off, or run less boost, as the torque produced is really going to work your gearbox.
its hard to know where the 1.05a/r housings limit is, as we were stonewalling the compressor and had a compressor speed limiting function in the ECU, adding boost wasn't really making any more power as the ECU was just pulling the target down anyway. it would be interesting to throw a 9174 core in there to see what happens with the 1.05 as it would be running near peak efficiency where this one is falling off.
I wish I had an EMAP sensor, but the wastegate duty was quite telling. at about 7000rpm and up we had to really start ramping the duty in to maintain boost target, whereas below this point it was pretty flat. compressor efficiency was really starting to dive up here so to maintain shaft power by increasing exhaust expansion ratio it looked like this:
(I'm using a 4 port 12w MAC valve and a 7psi spring in the gate, also using solenoid deadtime function in the emtron so real duty is about 12% more)
running the thing on E85 also makes the decision much easier.