Robert,
With a turbocharged engine, I treat any unexpected loss of manifold
pressure as an emergency situation that requires immediate engine
shut-down. I'm deathly afraid of engine fires. An unexplained loss of
MAP is frequently due to an exhaust manifold or clamp failure/ leak.
IFR over mountainous terrain at night might motivate me to take that
risk, but, under normal circumstances it makes no difference to me
what the engine can/will do with a single turbo because I'll be
shutting it down anyway.

--
Ron Laughlin
Legacy N44L (res)