Yeah, the "flutter" is the sound of the compressor wheel slowing down (against a pressure caused by the closed throttle body plate) when u tap off. 1. It puts huge strain on your turbo shaft/compressor wheel & vanes 2. It sounds cool but stuffs your turbo up eventually. 3. There is a less than optimum response from your turbo now as it has too spool up again from low speed each time you tap off and re-accelerate
If you want instant boost response put an anti-lag system in the exhaust system ala most WRC cars (and have the cops on yer a$$ as a bonus). Another bonus is you get to replace yer exhaust system rather often