Running ported or sealed...the age old question...
You need to first understand what a port does. I'll try to keep it simple and not confuse the matter with BS -
A port is a resonator that will "ring" at a certain frequency. Have you ever blown across the top of a bottle and had it "whistle" or "toot"? That's what a port does in a sub box.
All boxes have a response curve. As the frquecy being reproduced drops (goes lower in frequecy) the output of the box will go down (get quieter). A properly ported box rolls off slowly and will remain fairly smooth all the way to the port tuning frequency and then it'll drop like a rock. Also below the tuning frequecy, the box becomes unloaded. When this happens, the woofer only has it's own suspension (no air spring from the box) and if played at a high volume WILL damage the woofer.
The port is used to extend the low frequency response of the enclosure. Drawback, it will typically not play as low as a sealed box BUT up to it's tuning frequency (the port has to be tuned specifically for the enclosur & woofer) It will out perform a sealed box.
A sealed box has a very slow, linear (smooth) roll off all the way to it's lower frequency response but sacrafices some out put for the better linearity.
NOW - when the speaker is designed, it is designed with a certain type of enclosure in mind. Run the woofer in the type of box it is designed for.
SO:
Sealed box - linear, smooth and "punchy", but sacrafices some overall output (volume)
Ported box - louder, but peakier (not as smooth as a sealed), unloads below tuning frequecy.
Overall POPULAR opinions seem to be:
Sound quality - sealed box
overall SPL - ported box.
There are exceptions to every rule though...
I would suggest you look at some of the new woofers out. There are a bunch (10s 12s & 15s)that will go in a much smaller space and far out perform the CV woofer you have, even the 12s. Just a thought...