Wow, now this a nice sub-set!!
 

http://www.e39shop.de/pi1153147679.htm?categoryId=61


The complete set is about $1200 USD and comes with a Hertz Sub and Audison amp, plus wiring/adapter

The enclosure is about $519

Did I hear some one say Gruppe kauft! ;)

what is this? http://www.e39shop.de/pd133406313.htm?categoryId=64

That's a replacement door that allows for more flexibilty in speakers complements I think you can even install a sub there!

Wow, very cool! I wanted to try an Audison amp with my JL stealth box, may swap to it later. That enclosure would probably have you loose the spare i assume.

Yes it looks like Spare tire is removed for sure. The door panel as mentioned before will allow the speakers to be mounted in many places that may or may not sound better to you depending on placement.