When gear at neutral, rev 700rpm to 2000 rpm SLOWLY, no noise.

When gear at neutral, rev 700rpm to 2000 rpm QUICKLY, noise come at 1400rpm sounds like gears clashing inside the engine.

When gear at neutral, rev 700rpm to 2000 rpm VERY QUICKLY, cannot hear anything unusual, but don't mean the sound is not there.

I suspect at about 1400, ogura clutch engages the supercharger, which loads the engine, and creates this noise.

Car is 1.5 years old with 30,000km.

This problem also happens when car is moving. any ideas? Dealer thinks it's something called the camshaft advancer. What's that? Any merit to their thoughts?