Your top 9% and your excellent SAT score make you competitive for a non-auto admit, but the major you are applying to could have a big impact on your admission chances.
Pros:
1510 SAT score.......(excellent score)
Class Rank of top 9%......(right outside the auto-admit 6%)
IB Diploma.........(it shows rigor, and not as many applicants will have it)
Solid essays........ (many top-stat students do not put in the time to write
them and under-estimate how important they are)
Cons:
Good but not great GPA
Neutral:
"Pretty good" ECs
Best of luck!