That MTX box is kind of on the thin side of things, you want atleast 3/4 MDF to really have a sturdy box to get the most out of the bass response. 5/8's will hold up, but I see it flexing more than 3/4 MDF would.

You are better off just shopping through eBay for similar, if not better components to make up your own subbox/woofer/amp setup. That's my honest opinion.