What does the passenger side (UK) air intake do? I meant to ask this, I'd swapped my grill on it as soon as I bought the thing, but seen a bag stuffed into the recess? It hid behind the black rubber that sticks to the grill. I've left it open now with the new one but worried that I need some sort of rubber seal to stop water getting in? 

Hi d boy I believe the the left hand side wing vent is a fake and only fitted to make the car look right,,, it's the right one that's in portent as that's the air in take for the air filter

Cool Amy ideas on what the bag was? Should I replace the black rubber bung? 

Ha no idea what the bag is for and yes I would replace the robber bung 🚙👍