After the first summer with my 156 I had the windows tinted. Like you I went for the metalised tint. Max tint of 35% in the side and rear windows. What a difference it has made to the temperature buildup inside the car on a sunny day. Before tinting the AC could not keep the interior cool enough on a hot sunny day even in Wellington where 20 deg C is considered a heat wave. You can feel the difference in the heat coming through the windscreen compared to the side windows.
Perhaps Alfa could consider fitting heat reflective glass. I have been told though that this glass also reflects radar signals rendering radar detectors ineffective. True or not?