If you can reproduce the noise whilst stationary, it might be a great help if you can get some one to give the car some revs whilst you poke your head under the bonnet and try to locate the noise.
If you are certain it is the heatshield, if you have some gloves and don't mind risking it, you might be able to apply some pressure to the heatshield and see if the noise still occurs.
Or if that is too risky for you and you have some spanners at home/work, it could pay off to check the tightness of the bolts holding the heatshield in place.

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2015 Forester XT Premium
2020 VW Tiguan Allspace
teejay: If I wanted a comeback Id wank in front of a fan

I havent tried to reproduce the sound stationary. Ill go try that.