You'll be surprised.
Back in the day I ran a $30 'computer subwoofer'.
Was something along the lines of Edvan or Kingwood, I can't remember.
Anyway, it was cheap crap, and the 4" speaker put out nothing more than half-assed midbass.
So I decided to stick a small roll of tape in the port of that bandpass box, and guess what. I got rid of all the boominess and actually did reach around 48Hz just by reducing the port size.