Selector bushings arent a must do really, it's more of a feel thing.

For the paddles, you will need the paddles themselves which you can get as a complete wheel (E46 SMG steering wheel), or you can retrofit various other car's paddles which involve cutting into your existing wheel.

You will need the heated steering wheel clockspring for the connection point. If you already have the heated wheel and thus the clockspring, you may lose steering wheel heating, but I am not sure.

Then you just run wires from there to the selector lever and tap in to the +\- wires. You will need to manually move the selector to sport before the paddles will work.

Someone also makes a module that will allow you to enter sport/tiptronic mode by pressing the paddles simultaneously. That will probably need a bit more splicing. No idea who made it and how much, just saw someone in another forum selling his for a few hundred bucks a few weeks ago.

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04 X5 3.0i auto
03 X5 4.6is