Retrofit OEM subwoofer?

So guys my B8.5 has no subwoofer I would like to get one (OEM) and install it.

I made a quick search on Ebay and I can only find for B7. I may ask Audi for a price but usually we can get cheaper online so If anyone knows a place let me know. Also do you what's the part number? (Audi always ask for that)

Once I get it, do you know any guide for the installation.

Thanks in advance

Audi Toby! said:

Have you looked up in the boot under the parcel shelf? I thought they all came with them.

Click to expand...

Yeah, there is a place for the subwoofer in the top but it's empty...