I did this on my LCR a couple of months ago. No issues with paint damage on the bonnet so far and I have been for a fair few "spirited" drives since.
Just be careful to keep the little plastic clip things, they can break when you take them out and it's easy to drop them into the engine bay - keep one hand directly below in case you drop it. If one gets stuck in somewhere that gets very hot the melted plastic might cause issues.
Slightly increased induction, turbo and dump valve noise, certainly not to chavvy levels tho. Can hear the valves tapping away and the charcoal can too a little more but not really when you're inside the car with the windows closed.