its not really excess pressure though.
everything accept a vacuum has pressue

hence why you didnt seem to understand vacuum leaks the other week


here's a twist on it then.. i think we've done it before but...
external wastegate - lets say can flow whatever you want exhaust gas wise
little compressor wheel turbo and little exhaust housing, and external wastegate, can the t3 for example be set to run 30psi volume, with the wastegate open taking away the greater exhaust gases.

and what would happen theoretically then (as in supposing the t3 was still in its effiecency range and not overspeeding or what have you)