I posted this on the F3x forum but forgot to list here as well...
I'm selling my a sub enclosure that I purchased from another forum member. It fits a 10" subwoofer. It is not an Music Car NW box. Their box sits on the passenger side, above the battery. This enclosure sits on the driver's side, in the cubby opposite the cubby above the battery.
For anybody who might want an Audiomobile GTS subwoofer to accompany the enclosure, I can include it at a small additional cost.
Feel free to PM me with any questions.