Hey- that's a great question! I only had it out on the highway for some short stretches up to 60 so I'm not sure how it would sound at higher speeds. In either case, I didn't think it was any louder than some aero cross bars at lower speeds.
Decided to go a different direction for my Big Bend so I am selling this rack/platform. Everything is in excellent condition and practically brand new. Size is 60x54. This rack has never been loaded up even! For $500 you get the platform with accessory cross bars, ski carrier, and universal...