I've got a 1.8T A5 with the 19" Y wheels. I actually prefer that config to the standard 18" sport wheels that were on the loan car I had for a 3 day test drive - the car just feels a bit more planted to the road.
I wouldn't worry about them slowing you down at all, the car is not slow at all.
I wouldn't worry about them slowing you down at all, the car is not slow at all.