Thanks for responding, appreciate it. It's hard to tell from that link I posted but the lip hangs vertically across its width. Almost like a small ducktail spoiler but on the bottom of the car. So I'm unsure but it SEEMS like the air would flow under that lip, with a turbulent lower pressure area behind it, as opposed to being pushed out to the sides? I'm out of my depth here which is why I posted.
I don't have any problem with cooling and was wondering if it might reduce lift slightly (by smoothing and speeding up the underbody airflow) if I removed it?
I understand where it fits, and you're not wrong, it will make a low pressure area behind the it, but, depending on how low it hangs, there will be some pretty good interaction with the road, so we're not just dealing with free-stream air. How much gets shot laterally and how much continues to travel longitudinally is really one of those things you'd have to test to know. *IF* is gets rid of some cool ambient air and then replaces that with some hot radiator air (lower density), then it might not be too bad of a deal. Someone put it on there for some reason, so I doubt it's complete ballast, but, at the same time, I'd hesitate to try to guess at its overall contribution by just shooting from the hip.