Give that man a cigar. I expect the bass hump is there to give the M3 more apparent bass, and it does that very well.
I have no doubt the amp issues on subs has caused a lot of concern and effort at Axiom. Keeping the design in house gives you a lot of control, but also has its downside. Axiom now has to worry both about design and production, and production is a whole other can of worms. The amount of resources car manufacturers throw as manufacturing process and quality is mind boggling, but they have a lot of volume to spread the cost over.
------- Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!