Reading that you can see that we have already been reading that...
and even posting at it
Increasing the volume of the stock enclosure and upgrading the subs makes wonders. Moreover, the location below the seats is good for performance minded driver (the extra weight is low and in the middle between the axles. Some like to save the room in the trunk as well. Moreover, upgrading the underseat subs can be applied in all the 1, 3, 5 and 7 series. Someone should have a good business by providing upgraded under seat enclosure+sub combos.
(If you referred to Etik being able to ask from you, I agree that at the quoted price it might have made sense to ask you...)