The difference in steering feel is night and day with servotronic! This is by experience. My 2003 3.0 steering was reasonably tight with stock 235/65/17 wheels, but after I upgraded to 255/55/18 it got uncomfortably heavy and my wife (No comments about gym please) was not able to drive it. Period!
Around same time I was looking to get her 2005 4.4. She liked the car, but heavy steering was a showstopper. Being a good husband, I promised to address this “simple” issue and I did it with swapping steering rack with the one with servotronic. Before I dive into the technical details – the end result is very light steering at the low speeds. I liked it too, so I converted my 3.0 as well.
Now some technical details:
I got remanufactured Cardone racks from “Partsgeek.com” (they do not include servotronic valve itself). I just checked their website and they no longer have them, but you can find it from other sellers for under $400. I think it is Cardone part # 26-2818. I can confirm this if needed. The servotronic valve itself is $170 from partsgeek.
The installation is straight forward, just little tedious – you need to drop sub frame and slide steering rack to the side.
I did quick coding with NCS Expert on GM3 module to enable option 216.
As of today, I put over 40k miles on 2003 3.0 and over 12k on 2005 4.4. Both work great!

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2012 X5 x35i My new toy
2005 X5 4.4 Her's (Retrofitted Servotronic Steering Rack)
2003 X5 3.0 Mine (Retrofitted Servotronic Steering Rack and Heated Steering Wheel)
2001 M5 Son's car
2000 540i 6sp Sports pkg, supercharged. Son's car (Sold)
2001 530i (Sold)
1999 528i (Sold)
1975 2002 (Sold)