530d touring, cables and woofers

I just bought a 530d touring from 2000. There is a radio in it (origignal
BMW) Now I would like to put some more sound into the car.Not a big woofer
but a small one. As I am not really familiair with BMW wires I wonder if
there already is a connection at the back of the car, in the boot. The CD
player is in the back at the left side. And the battery on the other.

Looking forward to your answer.

Huibert Verschoor
Haarlem, The Netherlands
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