The lightest and thinest bonnet I ever made for the Pulsar is mine...it flaps around so much the chap who does my mapping always wounders if its going to fly up.....in 5 years is hasnt so far, and neither has any others I know of. Den has also run one for many years.
It already has wood built into it right around it and across the front and middle, I have seen Escort Mk2 F/G bonnets rise much higher than that, you could get your fist into them. Also have a look at some old Special saloon pics there panels used to flap and gap like mad. They used to tape the joins as well.
Have you blocked the 2 vents in the top grill ? (where your nissan badge is) I have also made a plate across the slam panel and run mine with very little gap in the front its almost touching the lights and middle grill.
Increase drag is not a great problem when you still have the large vent above wide open, imagine how much air is flooding in there, block that too, (Carl can run a flatter bonnet) you could build in extra strengthing alloy tube for example but you would add more weight, plus its not realy the material that adds the strength but the shape of the glass shape going over it, and using a core material in a bonnet? thats total crap, its not a bloody boat.
Its always going to flex to some extent it all depends how much your comfortable with? But with you bonnet pins I doubt it will ever to fly up. You could fit a small centre strap or clip if your worried, I would be veryvery suppriesed if mine does not lift a lot more.
Hope that helps, also shut your windows if you want less drag ...lol
