I am a big JL audio fan I will not purchase anything else.
Then buy a driver worth using, such as a W6v2. This driver will act as a perfect linear device up to it's rated excursion - not many drivers can do this - and it will allow for uncompromising sound quality and substantial SPL output. This driver is about $300 from discount sellers.
If you are not willing to buy a high quality JL driver for their higher price(
compared to what you can get from another brand like Infinity - with their Kappa Perfect subwoofers that compare closely with the JL W6v2 but for over $100 cheaper per driver), you will not end up with optimum performance and sound quality. It's just silly to go through the effort of building a nice cabinet only to use a low performance model subwoofer such as a W1. I would not even consider a W3 worth the effort. A W6 on the other hand, is a different matter: this is a special driver.
Even if you pay for the W6v2, you will end up with a far lower cost subwoofer system as compared to a retail unit of comparable quality. And if you use a well thought out cabinet and suitable amplifier, it would take a multi-thousand dollar commercially available home subwoofer to equal your results.
-Chris