TFSI induction fitted today, sounds ace until you get the weird sound if heard people on about, like a whistle, what causes it? Quite high pitched I think

I've the BSH intake and mine does this.Its possibly down to (on mine anyway) the t-piece that branches off to fit an aftermarket dump valve.It makes a whistle noise as it boosts hard at low revs and is louder when mapped.

Happen at the Top of the revs?

my old civic vti-s and civic 1.4 (ej9) used to whistle with induction kits fitted too. Something to do with the air flow

any pics?

I made a mistake and bought cheap BSR intake and it made weird whistling sound and because of one piece design it had resonance trouble. It also touched the master brake cylinder and made my clutch and brake  pedals vibrate under acceleration. Went back to stock intake.

No vibration issues, like I say all fine in fitting and sound, just that whistle, sure if read that the standard diaphragm or how ever it's spelt DV causes it but when you go piston it's better, or maybe I'm getting wires crossed

Mines fitted with a piston type dv and still does it. I'm running a single piece autotech intake but I'm looking at getting one made up with a bigger diameter pipe.