The phrase "be ahead" refers to having an advantage or being in a favorable position compared to others. There are various synonyms you can use to replace this expression, depending on the context. One possible synonym is "leading" which signifies being at the front of the pack. Another alternative could be "in the lead," which also highlights being ahead of the competition. "Ahead of the curve" is another synonym, which implies being ahead of the expected or usual progress. "Ahead of the game" and "ahead of the pack" are more informal idioms you could use when referring to someone who's doing exceptionally well compared to others in a particular domain.