Common misconception about ported boxes is that most people have only heard subs in non-specific ported enclosures that are too small and tuned too high, having a very peaky/"one note" sound.
A properly designed ported enclosure can sound better and play lower with a flatter response than a sealed alignment.
is it possible, sure, but overall 99% of ported boxes are not suitable for the subs they carry, do they work? sure, but sound quality wise you can get a much more even sound in a smaller space with a sealed box, only at the expense of slightly more power to drive the sub (which you have plenty of in a car). and on the subject of sound quality you should know that when you have a ported box it's frequency response drops off much faster than the same sub in a sealed box, due to the port, not great if you want a flat response.
sure, a ported box increases the efficiency of the woofer but at the expense of a uniform frequency response in MOST cases, and since I doubt most people on here have the slightest inkling on how to create a proper ported box, the simple answer of ported is better for one note and sealed for SQ is easiest for the majority to understand since this is the typical result. also since a ported box takes up much more space than a sealed one and for most of us space is at a premium (unless you bought an SUV and decided not to use it's cargo space for cargo) a sealed box fits easier.
...but saying ported is best for one note burps and sealed is best for sound quality leads me to believe that you don't know much about enclosures and design.
believe me i know plenty about loudspeakers, it is my profession, and not as some hacky dj, but as a sound mixer and technology specialist in the entire field of audio from studio recording to live concerts, to car audio.
but i don't believe silverblade cares that much about all this, so that is why i gave a simple answer instead of delving into the technical details.
and from wikipedia....
http://en.wikipedia.org/wiki/Bass_reflex (under limitations)
"Because of the complex frequency dependent loading, ported enclosures generally result in poorer transient response at low frequencies than in well-designed sealed box systems. Whether or not the effects of this in a properly designed system are audible are debatable. A poorly designed bass reflex system, generally one that is tuned too high, can ring at the tuning frequency and create a 'booming' one-note quality to the bass frequencies."
