I have an AGU 1.8T.
The car was serviced by r-tech back in jan this year with a full throttle body clean. Only problem they found was a split pipe, which has now been replaced. I think they cleaned the TB again when i had the ko3s fitted couple of weeks ago too. As for vagcom, I put the car through it three times last week, as I swapped the maf over, no error codes.
I dont notice any sound difference since fitting the ko3s, but the recirc valve seems to be louder since fitting the new maf.