you forgot one more factor in the myriad of answers, the duke's fuel pump is
located inside the cockpit, therefore is pressurized, pressurization in a IV-P
has a factor in the fuel flow, in my IV-P I believe its the reason for the
acute engine power loss when shifting tanks, the only way to avoid it is to go
high in the boost prior to switching, if you get a leak in the fuel pump like
it occurred to me you loose pressure. This event never happens at low
altitude, therefor my small brain tells me it pressure related. One more thing
to consider.

Andres,

 

Doesn't cabin pressurization just maintain a cabin altitude below 8000 feet, but no greater than sea level?  If so, wouldn't that be the same as flying unpressurized below 8000 feet?