One thing that you will want is the DSP harness. I am not affiliated with the seller, yada, yada, yada, but here is one on eBay. I have not seen one of these before:
http://cgi.ebay.com/ebaymotors/ws/eB...tem=8054838202
After that, you may need a newer MID that has the DSP controls. If you have navigation, then this is not necessary, since your nav computer will automatically recognice the DSP and give you a menu option.
You will also want to get an X5 subwoofer box. Then, you can splice the DSP harness into your existing audio wiring harness and look for the upgraded DSP speakers to replace your current speakers (optional).