checked the hoses atop the manifold? They tend to come loose as they are not clamped down at the factory.
when you checked the BOVs, the orange seals looked intact? those are what fail. post up pics if you got 'em.
pull the pipes off the turbos and inspect the turbo housing/turbine/compressor. try moving the actuator by hand. these internal wastegate actuators can fail over time resulting in power loss/ie no boost.
sometimes it is hard to tell if a pipe has cracked and is "leaky". So always inspect at the clamp area in a 360 degree fashion with your hand, see if there's oiliness anywhere.