yeah i know the wire you mean, its usually black or silver and supercheap and autopro sell it i think, its called car detail wire or some shit, i dont know much on the topic but id imagine you should be able to fabricate a plastic cover/scoop pretty easily, or even one out of sheet metal and spray it.
As for performance, im not going to say anythign at risk of being wrong and getting my head bitten off by someone that knows what they're talking about