mine has the same fluttering/wheezing sound that is most prominent at 3/4+ throttle when I'm passing someone ... it sounds like it is coming from the passenger side, and sounds kind of like if a piece of paper was stuck in a bicycle spoke, then when you are going fast, it hits the wheel brace part repeatedly

I can't hear it with the windows up and the radio on, but definitely hear it with the top down. I'm fairly certain it did not make the sound when stock. My car has 20k miles on it.

it doesn't make the sound at idle

I did a search on "bad bearing" noises, and it sounds nothing like the "rocks rattling around" sound.