on my 04 i installed a grill. it was aluminum billet. the front face horizontal billet was 1/4" with approximately 3/8" between. there were vertical supports that were tackwelded behind the horizontal billet. if i recall there were 3 or 4 supports. hope this description is adequate.

when i drove between 30 and 45 it sounded like the humming from a space ship. it was almost like twilight zone stuff. cant say it was a whistle.

to stop it i removed the grill layed it face down and every 4 or 5 inches ran a bead of rtv between the vertical supports. this was enough to deaden the sound.