I also wonder how the following affect the steering system to lessen/exacerbate problems:
1) lowering springs: changes geometry (slightly though), not sure if benefit or detriment, greater caster should make steering heavier;
2) spacers or aftermarket wheels (with greater than factory offset): enlarging track width will change things, not sure how wrt steering;
3) aftermarket tires: better rubber should increase/change the steering response, will change pneumatic trail and consequently self-aligning torque;
4) Alu Kreuz: should reduce deflection in the subframe and reduce compliance in the steering system;
5) alignment: caster, camber and toe should all affect how darty the car is and how stable it tracks.
I have upgraded all of the above along with disabling DSR, and no 48k8 update. 2013 early build FWIW (not sure of month, but took delivery in Dec 2012). Never had anything in the steering system replaced except for a front CV joint that was ruptured.
The EPS system consists of a lot of feedback control systems that traditionally functioned off hydraulic pumps/valves. Hydraulic systems were tuned by changing the size of springs (they function sort of like bypass valves within the boost pump), pulley's and gearing. Now everything is software, and negates 40 years of evolutionary engineering. I think these steering systems are trying to do too much/too soon, engineers see the ability to implement features like DSR (prevent vehicle from serving during wind gusts), but in the end just make things more dangerous. It's pretty telling how long this has taken Audi to address, because replacing steering racks and columns is not good for their bottom line, despite how some here might argue that only a "minority" have problems. Make sure you open cases with NHTSA if you are truly having problems.
Edit - Just remembered from a vehicle dynamics class I took that one of the most important attributes of the suspension geometry and how it affects the steering system is the scrub radius -
http://en.wikipedia.org/wiki/Scrub_radius
I believe you change the scrub radius through spacers, lowering springs and alignment changes. Might be interesting to hear what peoples setups are who experience the problem. From the wiki article
"When the vehicle has been modified with offset wheels, larger tires, height adjustments and side to side camber differences, the scrub radius will be changed and the handling and stability of the vehicle will be affected."
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