Can be common on these after some basic modifications have been made, such as snorkel, air filter and exhaust mods. Do you have any mods or is it totally stock?
Its hard for me to directly compare as I have the v6 but totally standard you can make it flutter quite faintly. Soon as you change to performance filter or add a snorkel its much more noticeable with a more aggressive driving style.
Any chance you can get a video and upload it?
Its not an entirely good thing although some people do like the sound. When your engine is under load, the engine is consuming air and your turbo is creating pressure (boost). Close the throttle however (as in when you would change gear or decelerate quickly), and the pressure maintains due to the momentum of the turbine wheel spinning incredibly fast, however the airflow has stopped because the throttle is closed. This situation forces the ‘intersection’ of pressure and airflow across the surge line as the pressure momentarily peaks and airflow virtually stops, forcing the turbocharger into compressor surge.
That fluttering noise is the sound of a turbo operating in compressor surge, as the compressor “chops” through the air rather than pushing the air into the engine. Whether you love the noise or not, it’s generally doing nothing good for your turbo performance or reliability.
There are a few things that can be looked at. I am assuming you don't have any error codes or an engine management light on?
Check your boost hoses, make sure there are no leaks or blockages in them all.
Check the EGR valve, make sure its not partially stuck (not enough to generate a code but enough to cause airflow disruption by being out of expected position).
Check what boost pressure you are maxing out at.
Check around the inlet manifold for any oil leakage.
