This is a shot in the dark but maybe the hose on your wastegate popped off?

I just listened to your video and I had the same noise coming from my turbo's. The secondary would not boost up. Now here are the things that I did. Make sure that the c clip is on the prespool arm (if thats not there then the secondary turbo doesn't get prespooled for the transition). The next thing that I looked at were to make sure the solinoids that are under the upper intake plenum are plugged in properly (you have to take off the vacuum chamber off next to the crossover pipe to get at them.) There should be a dot on one of the solinoids and connectors; make sure that they are not crossed. One final thing, did you wire open the wastegate when you did the non-sequential trans.? Hopefully this will help. I will try to remember what else I did and post it for you. But I eventually fixed the problem.

R.K.

im almost positive it isnt the BOV, because when i had the turbo's runnign sequential, the primary spooled fine to 10psi, and the BOV worked perfect... and also, if it were just the BOV failing, then i would get boost fine, until i let off the throttle, then i would get the surging... but something is keeping any boost from getting to my UIM and to my boost gauge. but the boost is making it through my intercooler to the elbow. that means that whatever is keeping the air from reaching the UIM has to be inbetween the elbow and the UIM. it also cant be an air leak because the pressure is staying in the pipes and being forced back through the turbos. if the air were just leaking out, i would not get the surging.

ok, the c-clip on the pre-spool arm is there... they are brand new turbos, with only about 3k miles on them, so i figured it would be, but i checked just in case. the solinoids are fine, i even tried switching them just to see if it had any affect, but it was still the same so i put them back. wiring the wastegate open? doing that would just limit my boost to 7psi wouldnt it? unless you are referring to the Turbo Control Actuator, in which case, yes it is wired open.

Did you check if all butter flies open on your TB and secondary? I would remove or keep the secondaries butter flies open to see if that's your problem. But check to see if all your butterflies open on your TB. Other than that I don't know what else to check

Do you have the stock rubber intake pipes? Here is a thought; maybe they are collapsing when the turbo's are trying to boost therefore you are not getting enough air flow to go throught the turbos. Also if you think its the tb just take off the elbow and see if they move freely. Just a long shot.

R.K.

Dunno if this will help but my mate somehow blocked his bov and did something with the wastegate lines on his S14 SR20T, and now it starts making whistle noise that comes out of the air filter! It sounds similar to yours but his one goes for longer... ssstototootoootoooo

I get this sound as well, but I always thought it came from my Apexi intakes. But then again I'm not boosting much on 2nd'dary either. hmmm...