Stock turbo flutter/surge?

[Yatta]

First, I searched, maybe not well enough but I searched before asking.

Currently my mods are:

2012 PU, CP-E Nano/d-flow, nviscid tip, autotech internals, Cobb AP with S-OTS stage 2, ran at Denver altitude (5280 +/- 500 feet).

This rig ran great and behaved well enough but I noticed what sounded like a boost leak under WOT in 4th gear or higher, I understand that the stock BPV holds well for most stock K04 maps but it sounded like a leak and I wanted an excuse to get a BPV, after a bit of research I purchased a syncronic BPV, I've seen a lot of opinions on this both pro and con but the idea of being open under partial throttle/non-boost situations was a big plus as this is a daily driver and as much as I would like to be at WOT all time its really not the best idea, being open should increase throttle response, decrease intake temps and allow slightly faster spool (not a real concern on a k04) I have seen claims about mileage but no real proof as of yet.


After getting the valve installed and adjusted I did a few WOT runs and found that my boost levels were on average about 1-2 PSI higher and the same test (4th gear and up WOT) I noticed a very slight flutter, I do not believe the BPV is causing this but to be certain I reversed the valve so that boost would hold it closed, (another nice feature of the syncronic BPV) this changed the sound of the valve in 'normal' situations, the whoosh was a bit more abrupt but did not change the WOT flutter sound that I heard, I tried to capture this with a phone and after that a voice recorder and neither were about to accurately capture the sound, dropping to a stock map has 'fixed' this but once you've ran staged maps stock feels pretty slow..


so after reading all of this my question is:

1. is this surge/pre-surge (real surge not throttle close build up but WOT surge).
2. what does real surge sound like on a stock k04?

I have searched the forums and found compressor maps and talk of tapering down past 5700 rpm,
but nothing in regards to what it actually sounds like when it happens, I would try to mount
a mic in the bay but really don't want to recreate this if its going to damage the engine.



Thanks