Welcome to the forum! I agree with getting a Bentley manual, and if you are at all tech savvy a cable from the "Romanian guy" would serve you well in detecting and correcting issues. I used mine to tell me that my middle left rear pdc sensor was out. I tried a stethoscope to listen for clicking, but couldn't find it! my computer told me right away, fixed the problem and cleared the code. pdc works great now!
how is the front suspension? (shaking when you apply the brakes, and its not warped rotors!!)

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2003 X5 3.0i (02/2003) sport package, Sapphire black metallic / Black Dakota Sport seats. compass mirror retrofit, trailer hitch retrofit, Prodigy P2 trailer brake controller installed, PDC retrofit, Lumbar support retrofit. heated rear seats retrofitted. Running boards retrofitted and subwoofer install in progress. 4.8is Brakes installed front and back. Bluetooth TCU installed, Rear Fog lights installed. Retrofitted reclining rear seat backs.