You might want to spray the bolts down with penetrating oil every day for a week before you do the job, those torx bolts can take a pile of torque!!! ive found (read article about safety!!) that using HIGH QUALITY hardened steel torx bits is the only way to go! ive broken more than my fair share of the cheap ones !!!
good luck!

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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.