When i had my rear alloy pulley swapped under warranty for a steel one due to wear ( which i assumed was the cause of belt noise) i was disappointed to find it made only a very slight improvement to noise levels.
i did use some dry lube ptfe sray on the belt which helped for a few miles but suspect the howling noise was in fact the bevel box as it got warm. It was a 2015 car so had all the mods, but unfortunately not a quiet bevel box.
