I've tried the phasing thing and what I get is either a lot of midbass or none at all. I haven't tried the time alignment to try to line up the midbasses to the subs though. The only time alignment I've done is with the front stage speakers (midbass, mids and tweeters). Maybe I'll try to play with this a bit more and see if I can get everything to play nicely.
09 E90 M3 - Interlagos Blue / Black Novillo / Sycamore Anthracite / Eibach / HRE