sewlow
Bitchin' Stitchin'
The only reason I'd ever port a subwoofer box is to gain low end response. It's not hard to get a subwoofer that will play at the volume that I want at 40-80hz but below 40hz it starts to get more difficult. If you want to get really fancy there's a program called WinISD that you can plug in all the (very) detailed specs of your desired subwoofer and it will graph and calculate the frequency response. You can play with the box size and tuning frequency and most of the time when I've messed with it the tuning frequency that gives me the flattest frequency response is below 30hz. Most subs in the proper box can play down to about 30hz so if you tune it below that (about 28hz is good a lot of the time) or actually just where the frequency response starts to drop off then you can boost those lower frequencies some which puts the point where the subwoofer starts to drop off down lower hopefully close to 20hz because that's about the bottom of what we can hear.
A box that is ported higher like in the 40-60hz range is going to be really "peaky" where it will sound tons louder at a certain frequency or a certain song than it does at everything else. IMO that sounds like crap. Theoretically a perfectly flat response would sound equally good on any type of music as it would treat all frequencies the same... But not all music is recorded with the idea of a flat response system in mind. A lot of Pop/rap is mixed with stock stereos or stereos without much bottom end in mind and therefore on a proper system the bass might be more than what the artist intended... anyway I digress.
You are a stereo god!