Do some subs defy the specs for porting?

This is a good example of the "SQ vs. SPL" question.  If you were to use the same size net volume for each type of enclosure...at 2.25 cu ft...the response in the sealed would give you SQ, and the response in the ported would give you SPL (with port designed as spec'd in the MANUAL).  Either type specifies wattage input at 300 watts.  The sealed nets a Q of .721 and an F3 of 38 Hz.

cb_response_kicker_cvr12.gif

The ported box has an F3 of 34 Hz with a much higher (7 db) response peak at 54 Hz.  The following was modeled using the equivalent round port to what is spec'd in the manual and shows some port resonance at 284 Hz, which may or may not be the case using slotted...

vb_response_kicker_cvr12.gif

You can see the difference in SPL and also the difference in response.  The sealed enclosure provides a nice output that would crossover nicely with the mid drivers.  The vented is for louder sub bass.  Depending on everything else in your system, one may sound better than the other, but for total Q the sealed box is the way to go.

plain & simple.......port it if you listen to rap techno hip hop. better low freq. response.   Granted the Power Acoustik KSW12 is the exact same sub... its a lot of air space but they sound great. My asst. "Candy " has three and they POUND

Gumby

As you can see if you looked at the graphs I posted, the ported does not, in this case, extend the low freq response.  (tcbturbosux, that's a generality....plain & simple).  In fact, the lows drop off quite steeply.

You have to look at the specs, particularly the EBP, of the sub (Fs/Qes) and see which way the sub should be enclosed.  If it tends to have a low EBP like this sub has, it is best used as sealed.  However, and we're still talking about THIS particular sub, porting does increase SPL particularly in the 50 Hz range, which is further amplified by the car's cabin gain.  If that's the way you have it and you like the sound and how it blends with the rest of your system, then it's good in your installation.  But I wouldn't agree that the specs on this one defy the sealed vs. ported calculations because you can't get a flattened response (within reasonable means) when you port it.