Originally Posted by wstar

There will be plenty of air movement in that area in general already, but getting the pressure and flow in the right direction(s) would be tricky. If any air is flowing through holes in the undertray, you want it to be upwards flow (sucking from the ground up into the engine bay), so that it's moving in the direction that helps rather than hurts front downforce. The potential problem is that, assuming the rest of the bay/hood is stock, there might be so much air pressure from the backside of the radiator that any vent you cut down there ends up flowing outwards and screwing that up. I really have no idea, all you could do is guess/test. If you had a hood vented to exhaust the pressure from the backside of the rad fans upwards (as is being discussed endlessly in other threads currently) the pressure would be a non-issue, but then you'd probably have plenty of airflow in/around there without cutting any new slits anyways.

Either way, I don't think it would be a good idea in any scenario to cut any slits/holes in the front chin spoiler.