Re: GSA audition pieces?
Any Ferling PIece will do. There is a great book out now with a cd recording playing example. Also, you may want to look into the Intermediate Solos for Saxophone Book and CD. This is written by Larry Teal and every solo is considered College Audition Worthy. You can also try Bozza Improvisation Caprice (pretty hard) and Sonata #3 by Handel (should be appropriate).
Hopefully, those will help
Good Times and Happy Playing . . ..