You didn't answer my question. However, let's go back and do this one bit at a time, painful as that may be.
I'm not saying you're saying that any gains will always be the same: However, am I correct in saying that you believe that, ignoring any degredation of the engine, that breathing mods including exhuast and CAI/panel filters will remain there forever without a remap? Is that bit correct?
To give a basic example that allows you to answer yes or no, a 2004 car makes 270bhp on a dyno, then is immediately fitted with a new free-flowing exhaust and is dyno'd at 280bhp on the same day on the same dyno: Do you believe this gain is there for good?