Yeah, they say it's the CAP grommets that can cause 'Prestige-whistle,'
@mtommer. I have a couple Tours and one of them does it. But Khachanov's serve sounds more like a slide whistle than a whispering Prestige. And I hear it on every single serve but never on groundies, not even on overheads. Hmm...
I don't remember hearing this sound when he played the H22. So maybe it's a Blade 98 thing? But on every single frame?