I had originally installed a sub in the factory location - with dynomat, polyfill, etc... and it sounded like crap. I just bought one of these boxes, since it will fit nicely in the trunk of the 350z, and it will have to do until I can find a good custom box to go with. (It was 50 bucks, with free shipping, on circuitcity.com)

 

I just got this box wired up in my trunk. It sounds great!

Clean, tight, bass - with no vibrations.