Geez go away for few hours and everybody chimes in...
I don't think Subaru had power in mind at all when adding AVCS, their likely target was emissions and maybe economy. The JDM STI may have exploited it for a different reason.
Certianly overlap at high RPM can help power up top, so I can see how clark found some power up there. On the other hand if you are at the edge of "reversion" keeping the exhaust backwash at bay would be good too. I think a lot will depend of the turbine, boost level,.....
More fun on the dyno to come.