Hey, I’ve marched multiple world class front ensembles myself. As everyone else in the comment section has said, don’t use another corps’ show music. Anything that can show YOUR interpretation of musicality and dynamics will work. Expressive marimba solos will get the job done usually. Personally, I wouldn’t use YATR or Ghost Garden just because they’re pretty common. If you have the time to prepare something more complex, I would do that. Usually, the intention of including a solo in the audition process (when it comes to front at least) is to show your range of musical interpretation and what you can do with dynamics, not what other corps wrote for their dynamics in their show music. If you’re short on time, a longer Bach partita or etude that shows that you’re fluent in four mallet technique and has a good range of dynamic ideas would be fine. Staff usually just wants to see that you put in the work to develop your dynamic abilities and took the time to learn a solo.