Horn Sound during 6+ psi pull (After FBO Install)

[dilla17]

Please view the short video of my car for the sound in question.
2012 BMW 135i N55 89,800 miles.

This weekend, i have installed the following:

VRSF 7” HD Intercooler
VRSF N55 catless downpipe
VRSF lower and upper charge pipes
BMS intake
MHD Stage 2+ 93 OCT

During WOT, car will reach ~16psi of boost, no more.
When the boost pressure gets to ~6psi, the horn sound will start.
I double checked all my connections, and all seemed fine. Should I be getting higher psi with stage 2+? I notice my boost value will dip negative (-0.8 max) at first moment of WOT.

My concern is I slightly bent the rim of the outlet pipe from the turbo (inlet of intercooler) while popping the t-band. The flexible connector fit easily over it, but I’m sure a small angle of the pipe juts out into the middle of the pipe, creating a pocket. Could this be my culprit? Car drive and feels great otherwise.

Other possibilities:
Downpipe: I started and revved the car after the downpipe was installed (all else stock) and didn’t have any issues apart from small amounts of white smoke.

Turbo seals could be blown, as oil was in my charge pipe and intercooler.

Turbo could be failing.
My filter housing seems to be leaking also, I’ll fix that next week.
Intercooler: connection not good enough?

BMS Intake: double checked connections, all good.

MHD Stage 2+: I was Stock with stage 1 93, no issues whatsoever. I’ll try re-flashing to stage 1 and see if the sound replicates.

Any input or experience is appreciated. It’s hard to enjoy my car when it sounds like a 4-wheeled kazoo.

[dilla17]

Update:

Turns out the clamp on the pipe exiting the turbo was not flush. Re-adjusted and tightened more, no more kazoo sound. Hit 22 psi according to the MHD monitor. Car pulls very hard.