Than why my first turbo is turning off around 3.000 rpm - I am sure 100%, I can feel that and hear as well.
What could be broken?
I've noticed that: if I accelerate from 1000 rpm up, at 2.300 rpm 1st turbo kick in and around 3.000 rpm it goes off but if I stop accelerate for second and start again (3200 rpm) it will kick again and turns off after few seconds and again if I stop accelerate for one second (3200 rpm) and start again it will kick. If I do not stop accelerate it would not kick.
There is a pressure drop between the transition from #1 to #2. This drop may feel like #1 is shutting off, but what is happening is once a certain rpm is reached a valve opens up to allow #2 to come on, this valve when opening and filling the #2 turbo with air takes some pressure off of #1 which causes boost to drop and then kick starts #2..this where you get that big kick in the ass!