Ran the forge for a bit and it just made a big ass woosh not any flutter, all other dump valves will do the same. It did throw my STFT off which is why I ditched it though. Flutter also isn't the best for a turbo as it does put a bit of extra stress on the bearings. The flutter is a turbo going into surge which is bad. Ideally, you should have no flutter from the DV just a woosh if it's a full vent.
Now if you wanna hear flutter you can fully disconnect the DV. DISCLAIMER - I don't take responsibility if something breaks, it will also throw a code, for turbocharger bypass circuit.
Now I did this on my old IS20 for a few weeks before I swapped it out, cause why not. With no DV it sounded like a big turbo supra with the chu chu sounds.
Did this put extra stress on my IS20 yea, did it affect its life it's hard to say.
This is a good read on what exactly the flutter sound it
https://themotorhood.com/themotorhood/2016/3/14/p6rwfjc50rjfsr2vtqkk3njyfv84bn
Also, the forge valve is not electronically controlled but vacuum operated, and tbh you really should just stick with stock on this platform.