^I see no harm in putting b16 on CNG, but the purpose of swaping b16 or any other performance engine dies when you've to use cng on it. And once you start using cng, you'll never get same performance while running on petrol that you used to get earlier, before putting cng (I'm not techinical to know the reason for this but I've experienced same)
btw nice dig, but it's good that you've not created new thread 