[Freon]

I don't think it's unreasonable to have a small electric compressor to reduce lag. Now, it still takes a ton of power to compress air just half atmosphere at even moderate mass flow rates (thousands or tens of thousands of watts, did the math on this before, it's not pretty), but for a hybrid that's less of a concern since the high power infrastructure is already there. For a non-hybrid, that's a lot of extra current that needs to be controlled and might require a special battery. Either way, there's a lot of engineering in tuning the thing to integrate smoothly with the rest of the engine and exhaust turbine turbos.

Definitely adds complexity and cost...