[1795]

Like Jeff (1985 CCX), I run with them open, albeit mine is just a race car. I was running the mesh screens initially but was told that even they are restrictive and will cost you about 50 HP. I can attest to that, as after I removed the screens there was a huge gain in performance.

If you will be driving in sandy areas or on gravel roads you might want some filtering. With a race car I am rebuilding the engine every couple of years so getting a little dust in there is not as concerning.