Turbo Flutter
 

I recently purchased a Turbocharged 2015 Scion FR-S (Automatic).
It pulls smoothly when under full boost, but makes a fluttering noise (audible in the attached video).
What is causing this noise or what should I try to narrow down the source?

https://photos.app.goo.gl/3Nyjx5VS1s75xoeg9

Specs:
- Full MaPerformance turbo kit
- Delicious tuning flex fuel kit
- Borla catback exhaust
- Open dump wastegate
- 350 wheel horsepower
- 12 lbs of boost

Sounds like wastegate flutter

Any idea on how to mitigate the flutter?
Assuming it is caused by the wastegate.

Frequency of the ebc needs to be tuned higher.

This is your EBCS frequency.

Just to clarify the statements already made about the EBCS frequency, this is not indicative of an issue with the car/setup. Whoever tuned the car can increase the wastegate frequency to turn the BWA-BWA-BWA-BWA sound into a BWAAAAAAA sound, but the only difference will be the sound. The car will otherwise drive and feel more or less the same, but adjusting the frequency is entirely preferential. If you want the wobble, keep it unchanged, if you want it smooth, increase it. A setting between 20 and 30 Hz would make it smooth.

Ahh yes, it pulls smoothly, I am just not a fan of the sound and would prefer it to be smooth.

For anyone curious I figured out what the source of the noise was.
The previous owner who installed the turbo kit routed the boost controller incorrectly.
It no longer makes jackhammer noises!