From what I know, The carbonfibre bonnet needs a metal core, I.e basically has the same strength as a normal bonnet so on impact the car crumples like it should to resist injury to you, peds and other drivers/cars
Now we all know skylines have shit crumple zones and dont pass crash tests, more often than not if u crash it hard enough u'll have half a engine crushing your legs.
Hence why they are not allowed into the US.
The main reason why they are illegal is because fibreglass shatters on impact, carbon fibre does only on seriously hard impacts.. its almost or is (im not quite sure) as strong as some metals, but does not share its crumple abilities. Basically if youve got a fibreglass bonnet with carbonfibre shit will go everywhere..
On this point, if your bonnet is actually plastic and has carbon top layer, is this legal?