I was looking through Evolution Motorsports site, and came across this:
http://69.59.165.43/evo/Pages/warranty.asp

How true is this!? When buying the car, the salesman (which had a a4 w/ LOTS of mods) said that most aftermarket parts do infact void your whole warranty. I'm just looking to get a new intake, and flash my ECU (prob revo II or apr), and MAYBE exhaust in the future...

 

its true, keep your mods hush-hush when you are at the stealership...

 

Thats wishful thinking in that statement.
The presence of aftermarket parts in a car is not the problem with warranty claims or with the dealer, but its fairly easy for a dealer to point to a any non-factory components that's anywhere near a failed original-equipment part can be fingered as a reason for warrenty claim denial. Some state's BAR (bureau of automotive repair) certify aftermarket parts as acceptable to use in specific vehicles on a annual basis. The reprogamming of software is a interesting subject because the dealer could readily deny a warrenty claim for particular vehicle problems if found out.