The new 2.0 motor makes great power with a tune and supporting mods. The stage 3 kit is not that new, but people have started to install them on their Golf R's. TC Kline is in Columbus, I go to HS Tuning in Westlake and then DubWerx in Cincinnati. Those are your options for APR.
For the A3, similar to my GLI but slightly different Gen3 motor I would recommend some summer tires, springs or coilovers, ECU and TCU tune and the car will be a blast around town. I don't track it, but around town it is very quick. Eventually I will go stage 2 with the down pipe, but I'm very happy with it right now.