Originally Posted by timmafod
With respect to being at stoich under boost, with the factory tune my car did remain closed loop/14.7AFR until around 3-4psi.
That's what I think did most of the damage on my car. Not the stock tune but once I cranked the boost it exacerbated the situation. I applied the OL/CL fix long ago but the damage had already been done ever since the first turbo went in 2005.
I continued running the same MBC after my turbo/FMIC swap and logs showed I never got into positive pressure while still in closed loop.