Adding a factory sub to a non DSP system?

[patrickkc]

I'm deciding if I want to buy a factory sub from a member on here, but I'm not sure if the sub is plug and play on my car. I have a 2005 3.0 with no DSP and NAV. He says some x5s are pre-wired for factory subs, but he wasn't able to find the harness on his car. I tried looking and found a blue plug on the right compartment, but turns out AMP labeling is just the company that does bmw's harnesses.

I've searched and searched and have no idea how that plug looks like or what I'm looking for. I've asked the questions in the FS section, but I'm thinking I would yield more results by asking here.

This is the blue plug I have found. It would be awesome if somebody could tell me what this plug does.