details dickfuck details, you still can't read!!! try this one I'll break it down barney style for you since it doesn't seem like you will be doing the standard 4 year highschool plan, you must either be sped or on some long term plan...

N/A = Naturally Aspirated = engine in which the intake air entering the system is at atmospheric pressure.

If you shoot n2o into the intake of any vehicle the manifold pressure doesn't become positive (i.e. PSI)

All Motor = N/A minus any fuel additives (i.e. n2o)

this is also the reason why n2o is not FI because n2o does NOT increase intake air pressure, it increases cylinder pressure through the release of oxygen.