Since the factory aero on my car was tuned for mpg I think, I previously cut out the holes behind the grill to let more air to radiator. It worked, but didn’t. Since there was no shrouding left after I deleted the factory active grill shutters, the air passing through the grill was able to go around the radiator and out the fronts of the wheel wells.
So I made this shroud for my radiator, oil cooler and intercooler today using kydex thermoplastic.
Oh this is a focus st.