To make it quick :

Boost leak when secondary comes online. After 4500 RPM a sound around the pssenger side starts, sounding like a duck call. I've checked the lines and check valves and they seem fine. Charge controller unit is working properly.

Looking for specific suggestions before I begin to dive in and rip everything out and go non-seq. And yes I've searched the forum.

 

check your hoses,again if you have already done so,taht should be your culprit.Pressure test?

 

The rubber intake hose that is between the front turbo and the airbox has collapsed on me, choking off air, and causing the sound you hear, and a loss of boost, not a leak. Fixed it by making a spring up and inserting it in the hose, similar to the springs in some radiator hoses

 

Found that hose to be a little loose. So I tightened it and will take a drive. Thanks for the info.

 

Well, I did a test drive and the boost leak is still present. Before I go diving into the rats nest, can anyone think what would make the high pitch sound during secondary boost?

Anyone know which check valve is under boost during 4500+ rpm's?

 

Take that hose off, and then test drive it.

 

Problem still there. Oh well. I'll live with it - or maybe sell the car.