I just got a 06' X5. I love the thing other than the audio. So I just figured I would change a few things about it. Here is what I went with:

Alpine PXE-H650 Sound Processor
Focal K2 Power Components for the front with an extra set of tweeters
Focal K2 Mid Bass for the rear doors
JL HD600 Amp for the Focal
JL Stealth Box SB-B-X5/10W1V2/BK
Alpine PDX-2.150 amp for the sub

I am not sure how this will sound once it is all installed . If anyone has any idea please let me know before I start LOL. Also if there is something I am missing. I knwo I will be adding XM and iPhone integration also.

The stock radio is just a business CD, no DSP and it has bluetooth.