Front camber is not adjustable on a standard A3 rear is adjustable.
OEM A3 run -0,5° of camber at the front and -1,5° at the rear.
If you want to improve handling you have to run more front négative camber.
In my opinion it's the best mod' ever. The car will be more over steering/neutral biased insteed of understeering biased, you will get much more grip at the front while cornering.
If you only drive on open road, you should run between -1,7°/-2,2° at the front and -1,5° at the rear.
If you drive on open road and on track, you should run between -2°/-2,5° at the front and -1,7°/-2° at the rear.
If you drive mainly on track, you should run between -2,5°/-3° at the front and -2°/-2,5° at the rear.
You can adjuste front camber thanks to longer front wishbones like Morego's or TT's, or/and adjustable top mounts.
If you change camber you have to make your car aligned by a spécialist as changing camber affect toe as well.