Where's the best place to add Mentos to Diet Coke for the most foam? How big are the individual bubbles? Has science gone too far?

Did you know that the popular Diet Coke and Mentos soda geyser experiment works better at higher altitudes? Or that the average size of the bubbles formed on the scotch mints is about 6I1/4m? Now you do, thanks to the wonders of science and those with a bubbling passion for it."