599 HGTE Sucking sound in foot well on full throttle

Hi all, I just bought my 3rd 599 and on the way home from picking it up I noticed a sort of sucking noise coming out from the drivers side (this a RHD vehicle) foot well by the accelerator and brake.

The noise was not there on my other two 599's so I'm now curious. Basically if I'm on the motorway in a high gear 4,5 or 6 doing 40-50mph and I push the accelerator to full opening the throttle bodies I get this noise.

Ir sounds like either a sucking or blowing and its only when the throttle bodies are in the full open position. Anyone have any ideas?

I went to the dealership who removed the wheel and the plastic liner as they thought the air box had a pipe that came in to the cabin but ended up discovering it was connected to the front arch vent so I'm still at a loss. I also just put brand new factory OEM filters in the car thinking that might be the issue but the noise i s still there...