Maintaining sump vacuum aids your oil pump. Bigger or baffled sump obviously allows "bubble settle out" too.
A well setup breather system/good sump crankcase vacuum and the subaru will not lose pump suction in hi "G" cornering.
Most engines where the driver (subaru specific) has said or has had the oil pressure fluctuation/loss during cornering have a catch can system to atmosphere. The original breather system also altered/disconnected.
I see two ways to sort it out, Bigger, baffled sump or Better crankcase evacuation.
Better evacuation also removes moisture,gasses,and oilmist,Less air being swirled around too.