well according to apr, its undetectable, that chip looks nice, i sent them an email with some questions, their performance chart was done with 93 octane, but i can only get 91, hope its still effective.
also about the boost gague the dealership aroun me said that if you end up having any electrical problems they will proboably blame it on the gague and thus void your warrenty, ut if the gague is installed and there are no problems with anything it directly effects then there is no problem. it is that way with any modification, if something goes wrong with your car as long as any mods havents effects that component of your car it will be covered
The only two things that will "void" a warranty are:
Tampering with the odometer
Taking the car outside of the US
Now, certain modifications could result in a denial of warranty work. For instance, if you chip your car and your turbo goes out, VW may deny warranty service. On the same note, if you chip your car and the sunroof goes out, since a powertrain mod has nothing to do with that, the sunroof will be covered.
You need to find a tuner friendly dealership and talk to them. Find out what they will and wont allow. Also, get to know the service advisor, make friends with him/her, get all of your maintenance work done at that dealership, buy parts from that dealership.. Basically, develop a good relationship with your dealer. That can go along way with warranty work. Im sure a dealership would have an easier time helping out a loyal customer with borderline warranty work than some ass that comes in demanding work be done for free.