Sunroof whistles ONLY when tilted and rear sliding windown open together going 60mph or faster. Whistling stops if I shut rear sliding window or open sunroof all the way. If I stick my hand through sunroof vent and push down on liner while driving it stops. To combat noise I've been propping something up there to push down and stop the whistling. I love the air flow with rear sliding window and sunroof tilted, not to mention the look. Any ideas why it only does this when tilted and at high speeds? Thanks for help.