Code:
I never updated this particular thread on this topic but I ended up abandoning this project. The bigger roadblock I run into is that cars are not prewired for it: this doesn't mean it can't be done but it would require a lot more work that I'm willing to spend on this.
You'd basically have to recreate the whole wiring: based on WDS there are some connection in the front of the car, some in the trunk, then run the wire to the pump under the car... Way too much work for me. And after is all done the unknown of the coding remains...
Found this in e70 thread. This is my prime concern. I searched a bit for a thread where somebody did this and had no luck.
I've seen in the past where somebody reverse an air spring delete.
If you find that thread you'd find most of what you need to know if you find that e53 unlike e70 were prewired for air possible. (I think the odds are fair this is the case. I used to find capped off wiring quite regulatory on my e53s).
For inspiration;
https://xoutpost.com/bmw-sav-forums/...uspension.html