went to school w some students (really really good pianists, they were the best at my school) that tried and didn't get in. the feel is that the auditions are almost a necessary formality since they probably already know before hand who they want and plan to let in, but in fairness give the mortal plebeians a shot, also gives them a chance to if by some miracle the caliber talent they look for is not on their radar , that they see a missed hot shot and grab them up.
i think others in the past have echoed similar, that it is highly unlikely that if you don't already have some pretty serious critical acclaim or performances and are recognized as a rising star or truly unusually gifted or have a highly recognized (internationally) teacher that has connections/clout and recommends you to them, that it's not likely, but i 'm sure it's a good experience and you should audition, but i would honestly use it as prep for your 2nd and 3rd choice schools.
Curtis Institute in Philladelphia?