I'd be really afraid of turbulence getting into the MAF sensor and causing all sorts of miscalculations in your a/f ratio. Thr screen is supposed to smooth out the air flowing through the MAF body so that an accurate measurement of the weight of the air entering the engine can be obtained, or so I've been told. Even having the radiator fan blowing air across the filter element is bad (those of us with open conical K&N's know this). I'd leave the screen alone and look to make horsepower somewhere else, preferrably with an intake, heads, and exhaust. A bigger TB and MAF meter wouldn't hurt, either. Hope this helps.
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Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch