It's part of the premium sound package I think? DSP+10 speakers+sub... anyway, it's on the righ side, you can see 2 subwoofers... by the way, speaking of sub, don't you feel guys that it kicks in at a veryyyy low frequency? I mean unless i play some humming low freq sounds, i can hardly feel that it is kicking in, the surround speakers do all the job until 50Hz maybe (i'm not a sound expert though, so if anyone can give us more technical details...)

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BMW X5 3.0si 2008
Premium Package
Light Package
Navigation
Reverse Camera
Rear Sensor (retro-fit)
Comfort Access
Spare Wheel
Power folding mirrors
Voice Control w Bluetooth
Power trunklid

BMW X3 3.0i 2006
M Aerokit
M Sport Package
Navigation System
BT Handsfree
Xenon HID

BMW X5 3.0i 2001 --- SOLD