The final cut of the 9th episode of the Tesla Motors Club Podcast, featuring Chad Schwitters, the former president of Plug In America, is now available. You can watch it now on YouTube or listen to it on all major podcast networks.
I think it was overpriced for what it provided, especially given that the "premium" audio package seems to be standard on Model S vehicles now. The subwoofer in that package is generally fine if you want balanced audio. If you want to focus on more bass output, you'd probably be better off spending the money on a solution that (perhaps) goes in the truck storage area.
A fellow Model S owner told me in discussion that you can remove the factory premium/UHFS subwoofer and replace it with a SoundQubed HDS2 subwoofer, add an amp, and there is a significant improvement in sound quality.
I have not looked into it further than that, but maybe another options. I know the sub is less than $100 bucks, then amp. So definitely more cost effective than the NVX sub/enclosure.