[C. Ludwig]

Nissan GTiR is one factory application of forced induction and ITBs. Like Ted pointed out, the big downside is the higher ratio of throttle plates and shafts in the air stream to disrupt flow. The upside is, like any ITB setup, throttle response.

You'll need an ECU that can do TPS and MAP blend tuning. The vacuum signal behind the throttle plates usually isn't much use as a load reference with ITBs. So you end up using Alpha-N (TPS) based load sensing and use a MAP correction map to compensate for positive manifold pressures. It's not hard to setup and tune, just different.