Alcohol content of the undilluted mix must be a whopping 50%ABV, since it's 2 parts Green at 55%ABV and 1 part Yellow at 40% (my bottle says 40 and not 43).
I absolutely agree on the matter of dilution, some soda improves the cocktail very much. I even suggest to give it a splash of lemon juice to balance the sweetness. If you think this measures will diminish the Chartreuse feeling, you could add some drops of Chartreuse Elixir.
Im afraid that my view on this is sacrilege
Chartreuse should be used sparingly and with reverence not like Watchtower confetti, thrown at you from street corners
Chartreuse, like a good Cardinal, should be in the background supporting the Pope of Alcohol, not centre stage on the alter of cocktails.
Amen brothers and sisters.
Great drink if you like Chartreuse; however, I will echo David on the importance of diluting a bit. Give it a good stir and serve with ice and it is delightful.
This is a great Chartreuse drink. It is well balanced, but I found it a little on the sweet side. I may consider holding back a little on the yellow Chartreuse for late night sipping, and use as is for after dinner.