It's the front bar that is whistling. Changing the air flow around the front load bar is crucial. One variable may be how far fore and aft you have your front horizontal load bar positioned (experiment with this one). Remember the air flows up and over the windscreen to hit the bar, and it will hit it differently in each position. Another variable is the section of your load bars (Yakima round, Thule square, some factory rails aero). Aero bars (thin section) like on my old Camry wagon are dead silent. Pretty weak, though. I'm using Thule on my new Volvo wagon. Very noisy at first, yes. I've put on two small accessories from Yakima that help quite a bit: Yakima Windjammers. Basically an airfoil that makes a little wing around the front load bar. Costs $6 (!) at a local bike shop (special order) and disrupts the air flow enough to help. The Windjammers would work better with a Yakima rack because they could be angled (horizontal only on square Thule bars). Fairings are the most certain cure, but I find them unsightly and have read they can damage the vehicle roof. I use rack systems frequently for ski and bike transport, and of course what you put on your rack whistles, too. Fairings cure that. Funny thing: when I would carry bikes in a fork mount on my old Camry using my same Thule system, they would whistle. But when I placed the read wheels flat on the roof between the bikes, nothing at all. Beautiful silence! Experiment freely. Small things can make a real difference. Best wishes.