Thee are eleven ingredients of the incense in the holy Temple. The teaching that lists them mentions at the end that if they would had added a drop of honey, no one could resist [it would be so inspiring]. So why did they not add any honey? כל שאור וכל דבש לא תקטירו No leaven nor any honey shalt you offer to the Lord your God.
This explains the simple path of the Gra. The Litvak yeshivot do not add nor subtract from the Torah because the Torah says so. [And in fact that is actually a verse in Deuteronomy: Thou shalt not add nor subtract from the Law.]
