Help mating Tang Band W6-1139SIF with proper enclosure.

A premade box that is not special designed for this driver will never be good. Cabinets need to be tuned to the driver. Those generic cabinets are mostly trash. Learn how to design yourself or build a full kit (cabinet designed for driver).

This driver need a 12L cabinet with a long port (2" diameter, 15"1/8 length) when doing it ported to have a low tuning. Sealed it will be not that low (50Hz F6). This won't be practical in build.

I would get an other driver if i'm honest, something like the Dayton RS225 does it a lot better for more or less the same price. The cabinet will be bigger (45L, but the vent shorter (2" dia, 11" length) and the bass louder and lower.
 
I shared the same concerns as well. I had read this sub likes a good size port opening and they tended to be long for such small enclosure size... but I came across the box I linked because it looked close to what I though would be needed parameter wise. I was hoping someone more knowledgeable and with better understanding of these things could help. I was really just hoping to use a couple of these to fill in my center channel in the 40hz to 80hz region... My center channel is an old Klipsch kv4 and drops like a rock around 70hz
 
When it comes to drivers with unusually large Xmax, I'll tend to go for a passive radiator solution. They take up much less cabinet volume, don't produce wind noises, and don't exhibit vent resonances.

The penalty is typically cost.

Chris