if you look under the lid on the snorkel attached to the bonnet, you will see a baffle, which is angled to reduce airflow, and most of the air bypasses this, and goes into the engine bay.
The carbonio does not have a baffle AFAIK, and therefore the flow of air is uninterrupted. This may not increase bhp, but it may improve responsiveness/ reduce lag.

The baffles can be carefully removed/alterred to improve airflow, and is much cheaper than a carbonio.

HTP F-P