Originally Posted by jpatt006
Sounds like the EBCS is doing its job. Are you sure this is not wastegate flutter?
The EBCS will rapidly open and close the wastegate to regulate boost...and since you say there are no issues holding boost, it sounds like the EBCS is operating as it should.
This explanation is spot on. More than likely what you are hearing is the internal wastegate flap opening and closing rapidly as designed to regulate the boost pressure and keep it at the desired level.