well, there is no such thing as a jdm b18c5. b18c5 = us itr. b18c spec r = jdm itr.
now, the jdm itr motor doesn't have a pressure switch, you're right. and neither does the jdm p73 ecu look for it.
if you're using a different ecu, you need to get it chipped to not look for said switch. almost every management out there has the option to disable o2, knock, and pressure sensors.