Cheap dollar subs

[GlassWolf]

you're talking about front stage in the first statement. generally that means 6.5" or smaller driver. 8" if it's midbass.
Also IB, or sealed and not ported, so a bit of a moot point.
Also the enclosure for a sub when ported is going to limit the excursion, so that's not as much of a concern as with a sealed box, where excursions are far greater.