I think there is another thread where he says the high speed stability of the car is worse, as without a ducted bonnet the air from the radiator has nowhere to go.

It's also missing the front spoiler as well. For sort of thing to work properly, it would be lower at the front than at the back.

The ideal setup for your car Darren, would be a plate from the lowest front edge of your Wings West spoiler, gradually rising up back to the floor of the car.

The guy on prime doesn't fill me confidence that he has measured anything. His quote the 'brakes seem cooler, by seat of the pants feel', makes me laugh.