[Christ]

MAP compensates for manifold pressure by adding fuel. It doesn't care about flow.

MAP systems assume a basic map of manifold pressure versus known VE under OE circumstances, and add fuel based on that. It will run pig-rich because he's stuffing hot air in the engine under high RPM situations, to the extent that the O2 can't recalibrate the mixture enough to compensate. If he does it long enough, the cat's toast. Raw fuel in a catalytic converter is a good way to have a car fire, by the way. I've had it happen.