They look great! I must say I can appreciate the work involved in doing these.
That said, I've been in the technical side of the aviation aviation industry for a long time and I'd have to say that given the design of the new part, I'm not real sure how much you'll get a definitive advantage from it.
A venturi (which is what this design is) works by utilising Bernoulli's principle....airflow over a curved surface accelerates, and in doing so it drops air pressure at the point where the air speeds up.
You might notice the factory extractors have a "curved" outer cover over the front of the extractor....this is to accelerate the airflow and thereby lower the air pressure over the extractor relative to the air pressure inside the engine bay. This is how the vent actually "extracts" engine bay air.
Without that curved leading cover over the new vent, the larger surface area of the vent will still exhaust engine bay air (which is at higher ambient pressure than the outside due to the ram effect of air intake through the grills/radiator)......but without a wind tunnel test, I'm not sure that the new one would be any more efficient than the factory extractor.
Not meaning to have a shot at them or anything....just offering my thoughts, is all.
They look terrific, and I can definitely see a market for them!