Unfortunately I have no experience with Audi BUT why do you want to do this??
IF the car is staying NA then you may well lose performance as the intake velocity will be slower due to the larger ports and the cylinder fill less due to the lack of positive pressure supplied by a turbo.
The turbo camshaft may well be different as well.
IF you do change the heads then you will need to port match the NA inlet manifold as the smaller runners will harm the flow due to turbulence where the small runners meet the larger head ports OR use the turbo IM