Here's the press release:
They did the following:
- added OEM tweeter to center channel
- added OEM tweeters to rear doors
- installed 2 12" GTi trunk subs (bandpass box, IIRC)
- ran L7 amp outputs into MS-8's speaker level inputs
- used (2) 4-channel amps for interior speakers
- used mono amp for trunk subs
The only non-OEM speakers they used were the trunk subs! I tried to mirror what JBL did with the 325i. But I did not amp the L7 speakers, I ran them off the MS-8. Worked great.
Note: I believe the algorithm may have changed between this beta unit and the production units. There were reports of a key programmer having left the company and they basically had to re-program everything from scratch and that was part of the big delay in getting the unit released. So the BMW midbass problem may not have been present in the demo unit, and it may be a flaw that is still present today in the production units.