I think the grille splitter was only on street cars. RUMOR has it that the air was deflected up to create downforce, but it doesn't look like it would help much on that.
The splitters are probably supposed to divert airflow under the hood.
This guy has an adjustable and a fixed version.
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I would like one myself; his brackets are not made for Backdraft roadsters. They look like they could be adapted to just about any grille opening.
The air deflection might solve the percolation problem and set off your car's appearance, too.
Good luck.
Russell