[Richard O'Clery]

I love the look of the spoiler and agree it will cut a lot of air that would otherwise have 'packed' under the front of the car.

If air flow from the front air intake was not restricted by the radiator, it would seem clear that the nostril area should equal the intake area. Perhaps someone with more experience could chime in here, but I would expect that as the radiator would block some of the airflow the outlet should not be as large as the intake. If it's too big, wouldn't this mean there is a risk of the area behind the radiator becoming an even lower pressure area than it ordinarily is? If so, turbulent air could even come in through the outlets to fill this low pressure area, adversely affecting cooling efficiency, and the amount of stagnant air at the front of the car could increase causing extra drag.

If you do end up with a low pressure area here, perhaps you could bleed air in from the wheel wells (similar to the louver effect mentioned by Peter) to offset and get some useful lift reduction.

Sorry to wax all theortical on you Iain, but there may be some efficiencies to be gained with this kind of stuff that make it worth exploring a bit during testing. A couple of different nostril configurations, variable ducts and manometers might be enough to ensure the airflow is doing what you really intend it to. Air - a tricky business...