EDIT: e90 sedan only, does not fit e91, e92 or e93.
$350 plus shipping
Sub is dual 4 ohm, currently wired for 2 ohm total. VP Electricity enclosure. JL Audio grille. Everything appr. 2-3 years old. I'm the second owner. Had this running on 500 clean watts from a JL HD900/5 amp.
*** This is an SQ set-up ***
Corner loading "amplifies" the sound waves and produces extremely clean, up-front bass with very little to no rattles. This will not shake your car apart, but it will be the perfect addition to an existing L7 system or an SQ based aftermarket system. It will easily get as loud as two 10" woofers in a standard enclosure, minus the rattles. Blends very well with front stage, especially when polarity is reversed.
Note, the sub mounting flange diameter is slightly larger than the recessed opening of the enclosure. The previous owner ground the metal on the outside of the flange to make it fit into the opening. From what I remember the amount of metal removed is very little. You don't see this since the sub is fully recessed into the enclosure. I'm just mentioning this in case someone wants to use this sub top-mounted in another application, in which case the rough surface of the flange would be visible.
Thanks for looking!