i had the same thing
boxster constant noise from brakes - YouTube
turned out to be the ebrake line was meeting the wheel weights the shop had put on the wheel instead of using the tack-on weights.
zip tied the e-brake line to the arm and the noise was gone. got the weights fixed. the heat and weather eventually caused the line to work free again. even though the weights were no longer there, it still made noise. re-tied and it's well again. now i carry some extras in my toolkit just in case.
there is a snap you can buy that holds the line to the arm rather than zip tied. i have them, have never put them on.
Pelican Parts - Product Information: OEM-99965123002
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