I have added a sub woofer and amp to my 525i. Overall I am happy with the sound, but not really enthralled with the looks. (It is just an angled box). I would really like a custom enclosure in the left rear corner, similar to this.
http://mobile.jlaudio.com/products_stealth...php?fit_id=1577
I was thinking of approaching a local shop to make me one like this and thought to offer a group buy. Maybe we could get the price down. The JL box is $950, but that includes the woofer( the same woofer I already have). If there is any interest drop me an email. neil.schneider@comcast.net. In the meantime I will see if I can get an estimate. Attached is the box I currently have.

hey, whats up man, does thet encolsure come with w7 sub with what diameter, also does that price include only one sub and enlosure or 2, thanks man.

Hmm.. Count me in I think..

For $950 you get 1 12w6v2, and 1 enclosure. I am trying to get a group buy on a custom enclosure or the jl version.

e-mail sent! :)

Ok,
Still working on it. We need at least 3 guys to commit and the price would be about $300. Which is pretty good. The area inside the box is about 1 cubic foot. It would look something like this but be for a 5 series and on the drivers side.
If you guys would rather have the jl, which comes with a 12 inch sub(12w6v2), let me know.