Encouraged by some of the posts from you guys, I went for full flavor at 4 drops per 10ml without further dilution. I noticed a vast improvement in flavor, and despite all the warnings at ECX's website, nothing happened to me ..... Thanks everyone who made the suggestion. I did notice something that I already knew before - and that is going from say 5% to 10% did not actually double the taste. It only improved it moderately. Sometimes it even diminishes the taste when you go higher than a certain %. With that in mind, for those interested in reducing coil gunk, it might be best to start with 2 drops per ml and see how it tastes. You can always increase the drops later if necessary.