I'd be very interested to learn also...My 2018 R/T with only 3K mi on it, just did the same few weeks ago...Remains intermittent...and came about after a hard , full accelleration...Sound seems like a window seal air leak..but it is NOT...it seems to be underhood, and needs to be cruising at near hwy speed to cause it...and not repeatedly...Is your whistle like that ?