I can tell you only some of the bass comes from the 6.5, as I can mute all of the other channels and see what they really add. I don't remember if separating the channels when the amp was installed sounds different - too long ago. They won't move too much regardless (especially mine) due to the frequency and the limited range I have them running at.
Filippo - I'm betting you have to crank these down (spl wise) - but I'll take an efficient speaker any day. Hurry up and finish this - will ya - I'm waiting on your feedback to buy them.
Another vendor making speakers for BMWs (just to have all this info in one place) is ETON
http://www.eton-gmbh.com/en/products...o/bmw-upgrade/
No US distributors, but guy on 3 series forum gets these from Europe via ebay seller/distributor: acr-bad-hersfeld_de