1) my allroad is a lease... i'm very friendly with my dealer (2nd audi from them) and they are willing to look the other way was as long as i dont encounter any major engine problems (turbos, etc). audi of america owns the car, not specific dealers, they have nothing to lose.
2) when i install GIAC software i'm going to buy an extra OEM ECU... if i need to take my car in to the dealer, or when when i return it, i will swap the stock ECU with the GIAC one. i can then sell the GIAC one to make back part of the cost.
3) Not sure about APR, dealers are always coming out with new ways to detect ECU tuning. i'm sure they can tell even if they dont tell people
4) +80hp is well worth the hassle
