Has anyone contacted Audi concerning what modifications would void the warranty? I read that spacer most likely would not and that new springs likely would. I emailed Audi the question concerning spacers and am awaiting a response.

Modifications to your car cannot "void your warranty" (at least in the U.S.). Audi can only deny warrantly claims if the modification was the cause of the problem. If they wish they can be broad in their interpretation of what problems the mod might have caused, but they can't just void the entire warranty.

So they could deny suspension claims with new springs, but they couldn't deny claims for engine or eletrical problem.