The thing is, with this particular driver, you are going to have a small bandwidth by putting it in a standard ported design that is optimal. Any recommendation can work for a simple port calculation, but attention needs to be payed to the phase of the response and in this subwoofer, it would actually work much better with a sealed enclosure to be perfectly honest. Yes, output will suffer, but quality will be much better. The reason? You have to tune this driver pretty low to get a smooth response, NOT spl response, but for timing and such for accurate reproduction. The actual best passband for this sub is 25-62Hz, and as we know, the smaller the tuning, the smaller the bandwidth. Not that it will not sound good in a ported box, but not as good as in a sealed (preference not included). Not to mention that driver excursion will be exceeded in most bass reflex designs for this subwoofer at max power levels. It does require quite a large compression area as well, so tuning may be a factor when dealing with that excursion control. Just some thoughts about the driver of choice on my part.