Thanks Technic.
I'm glad that I got to do this blaupunkt installation because 1) I wanted a better performance out of my subs at a reasonable price/effort, 2) it got me to do the necessary research I would have never done otherwise.
Since I'm not an audiophile, I think I'm okay with the gained power from Blaupunkt for now. While I'm not sure if it's as good as 10 inchers in the trunk (I'm a bit embarrassed to say I've never been in a car with that set up), this was a fun weekend project, and I really like the remote bass control since I don't have to go into the idrive to adjust the bass level.
The only thing that worries me is blowing the subs by getting overly eager with the remote, as I suspect that warranty (related to Subwoofers) has gone down the drain. I'd like earthquake sws on my car, but at the moment it sounds like more work than I'm willing to put in. (getting under the front seats and putting in spacers to fit the speakers to the enclosure, etc.)
Until I blow my stock subs or get extrememly bored with their performance, I don't think I'm going to upgrade them.
Maybe ElectroVoice can answer this better. You said in your first post "Set the low pass frequency to about 90 Hz, setting the bass boost on about half way, and the remote bass level to about 3 quarters". That sounds like the amp will be pumping in more power than your stock subs were made to handle according to the table I linked above. Do you feel like the subs are handling them ok?
PS. If 40W max at 2 ohms, is that like 20W max at 4 ohms and 10W RMS at 4 ohms?
If so, then wouldn't it be 7.5 times, rather than 6 times the continuous power rating?