The O2 sensor doesnt work that way. It is reactive to the amount of air a fuel in the exhaust. thats it. it will operate in total vacuum out side of the exhaust.

If there is an exhaust leak before the turbo the turbo will not move the same amount of air the car was tuned for.since Hondas use a MAP sensor instead of a MAF. The ECU can measure the pressure but not the actual flow or weight of the air going in the engine.