My front air guides underneath the radiators are cracked and need replacing. It's made up of two pieces attached perpendicular to each other.
Part numbers for the cracked piece in the pic below are 996.504.504.00 (right front) and 996.504.503.00 (left front).
The perpendicular piece part numbers were provided by thom7482 - 996.504.603.00 (left) and 996.504.604.00 (right).