I'm using a Yakima rack, Kargo Master rack with a modified Yakima Fairing
My Kargo Master rack was very noisy too, so I made an air foil from a sheet of metal stripped from an old micro wave oven and riveted it on. It was a temporary solution until I could figure out something better. It did okay and did help cut down the noise a little. I finally bought a Yakima Fairing, cut it to fit my Kargo Master rack and made a few more modifications to it. It's done a great job and there's practically no additional noise coming from the rack compared to the noise I have driving my jeep without the rack installed.
I spent some time trying to figure this one out. It really has made a huge difference in my wind noise. Hope you find it useful or sparks some ideas.