Imagine the rear housing of the turbo at that temperature, the steel becomes pliable, almost like putty. If you don't support the manifold/turbo it will droop, the weight of the exhaust is helping this happen, along with hard cornering causing the weight of the mufflers to deform the housing using the massive leverage involved. Race cars don't have a full exhaust and generally use brackets over the engine to support the turbo in these situations.
It definitely doesn't seem like a massive stretch to me either...