ok, i have had a think about it, and after reading all ur posts, i have my own opinion on the matter.
For single turbo engines such as XR6T and RB25DET, what i posted previously still holds... that it is highly unlikely that turbo bits will get sucked back into the engine since the airflow is going outwards. I myself have done abit of fluid mechanics and if this exhaust flow was laminar then we would expect this result. On the other hand if it were turbulent flow then yes it could get sucked through. From wat i can remember, i think my mate said that up to the turbo is laminar and the turbulence starts at the dump pipe, but i will reconfirm with him.
What happens with TT cars such as the GTR (in my opinion), is that when 1 of the turbos blow, the air in the engine will take the easiest path out and go through the non-blown turbo. This will cause the air-pressure from the blown port to reverse and for theengine to begin sucking air in from the blown turbo, enough pressure that is, to send tubo bits back in.
I think this is what u were saying t04GTR.
This phenomenon would obviously not be a problem in single turbo cars since there is no other way the air can escape.
Plz correct me ne1 if what im saying is full of shit... but to me it makes sense.
P.S. I said my mate makes over 55K, that doesnt mean he's not making 100gs, I just don't want to post his exact salary up on a public forum