I'm having the same issue with a 2020 GT. it seems to do it at around 1750 rpm, whistle from passenger side (noise is heard coming out tailpipes). problem is it's a convertible with a 10 speed auto that's favorite rpm is around 1750! this can't be normal, it's really annoying and kills the top down experience. has anyone had any luck figuring this out?

 

tycomps2, you responded to a 12 year old post in the wrong year car forum. hopefully a mod will put this in a S550 forum to help you out. good luck

 

Moved to S550 and its own thread