Yes, it's noisy. And affects mpg, so remove them if you don't need them.
Here are the bars (and ski rack) on my M135i from various angles:
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Current: Macan GTS
Previous: 440i GC, M135i, E60 M5, Z1, 330d, 135i, Alfa 156 GTA, Mercedes 500E, Audi S3, Audi A3 quattro, VW Golf GTI 16v