Don't get obsessive about specs or T/S parameters. It doesn't better than these JBL drivers (although JBL is EXPENSIVE). There are tricks for making pro drivers such as this into a sub: take advantage of its super efficiency and typical room nodes. This means EBS alignment (larger box and port frequency lower than is usual) and crossing over lower than most people would do per spec. Think outside of the box. Trade the efficiency for bass extension. That being said, you would need a LOT of internal volume... maybe 3-5 cubic feet or more. (I haven't crunched numbers, but this is a guess, and your PEX DIY cabinet probably wouldn't work).
There are a lot of drivers with the right specs... but most end up sounding craptastic.