I have a 2007 civic si with a k20 in it. It runs and drives fine and the power is constant but whenever I rev up to 2000-2500 rpm I hear this tapping noise. And higher and it goes away. Any lower and it goes away. It will only make the noise while driving if you rev it to 2000-2500 in neutral or not in gear the tapping won’t occur.. hopefully this video uploads so you guys can hear it