There's some modification required to the top face of the sub enclosure assembly (to allow it to accept the 8" driver in lieu of the 6.5" one), but nothing too tough. If you can wield a jigsaw and a piece of MDF you'd have it done within and hour or so. I actually have a template somewhere for the exact shape required.
Gone but not forgotten:
325i M Sport (E92), Black Sapphire, Coral Red Dakota, 19" 225's, Seat Heating, 6FL and de-badge
Replaced by 6.2 litres of AMG powered C class.