I have for sale, out of my 2003 540i (E39), the trunk mounted DSP Subwoofer Box.
Attention.....just the carpeted box is available.....the subwoofer speakers from it are already sold.
If anyone has a use for it, I'm giving it away for $30.
It's in mint condition and I'm selling due to a BSW audio upgrade.
PM or e-mail me ASAP at email@example.com