I have removed my head after my timing belt died on my ATW 1.8t. The valves are definatly dead, but I am unsure if I can still use my pistons. There are some decent gouges and I was wondering if I should replace or just smooth out and hope for the best? They are on the lip of all four pistons.
Here are pics.

 

You can remove them to get reground but then need to know the thickness tolerance. And a good machinist.

Honestly? I would replace then regardless... You do have a Turbo that is hard on pistons as it is.

Shoot, if it were me, I'd have the block bored oversized and custom pistons made with valve-notches so this couldnt happen again and to allow a more radical cam.... then crank the psi to 28

 

I wish I had that kind of money to throw at this right now. But I think just getting it running again would make me happy.

 

Well.. the piston in the second pic has a pretty deep gouge... it prolly wont last if you get on it much. Remember, these things are aluminum and aluminum doest hold up well when damaged.