internal volume for sub box

If its recomended (by manufacturer) to have a sub box with 2.5 - 3 internal volume and mine has less (2.4), will my subs sound like crap?  How far can i be off from what they recomend before i can hear the difference?  Thanks

flashover95, the Q is likely over 1.0 unless you use the larger airspace.  This is a result of an overly sharp and generous peak in the output, probably over +6db.  What you hear is too much volume at around, most likely, ~50 Hz.  When you then try to compensate for the peak using tone controls (etc.), the low end of the frequency spectrum is further minimized.  The result is less-than-ideal response.

Manufacturers try to recommend the least amount of airspace requirements for their subs due to the limited amount of free space in vehicles.  They will often give you options of sizes while warning that going smaller than the largest will result in less low end.  The sound, though, will not necessarily be described as "crappy"...it depends on the gear and quality of install, all of that.  It just might not be ideal.