I'm just relaying what a knowledgeable Subie tuner told me about the wastegate flapper on IHI t/cs. Boost creep kills.
There's a company that modifies the wastegate flapper for that very purpose.
The little bridge of metal between the intake and exhaust valve on my G10? It wasn't just cracked there. It was gone. Big chunk of metal just gone. Blown In the catalyst maybe...
vaporized??? ...who knows? there were cracks between the ex valve and spark plug hole and all the way through to the sealing surface of the head.
My G10 got knocked the f#$ out.
It was only a $100 car that I got because the original owner could not diagnose a timing belt that was missing some teeth.
I wasn't too broken up over my loss.