Mark it out properly, tape up the bonnet and use a new tungsten carbide grit blade, no reason why it shouldnt come out ok. There's a small lip on the underside of the vents which can be used to mount it to the bonnet. I'll probably do my carbon bonnet at some point. Most likely I'll cut out a hole in some ally or steel to get the hole size spot on, then transfer that to the bonnet. Any tidying up or enlarging can be done with a dremmel.