HP to HK Sound: Door Wires

[IMAY2023]

As far as I know, it is possible, as long as you have an AUD (high performance) under the passenger seat, you can add the subwoofer. 
You will need to wire them up because the car does not come pre-wired in most versions. Then, you will need to use Orbit to enable the subwoofer.

Hi, yes I have the amp under the seat, and I already have the subwoofer thing sorted out and have already bought one on eBay.
Now I have a question about how to add the harman kardon center speaker.
I have read on some forums that it is plug and play, is that possible?

As far as I know, the high performance AUD does not have center speaker output. You'll need to replace your AUD to HK or B&W. 
If you upgrade your AUD to HK, you will need to rewire the front door speakers.  Because HK AUD, has a second output channel for MID + high. Your high performance AUD, has only 1 channel and woofer, mid and tweeter are all in parallel on the same one channel.