When did it start breaking down? After a mod? which mod? After a tune?
I find breaking down is usually a plug or coil issue, particularly when it happens at peak boost.
My guess is the electrical system (including the plugs) cant deliver enough energy to light the particular air/fuel mix you have in the cylinder at that boost/MAP pressure.
It could be caused by too rich AFR (If the mix is really rich, like lower than 0.8 lamda, it will be difficult to light)
Assuming AFR is sensible, i would guess electrical and in order of most probable, i would suggest coilpacks, plugs, wiring, then ecu.
You can also gap the plugs down further like 0.6mm, that should give you a clue as to what is going on