Chances of Getting into SIUC?

Both my parents are SIUC alumini. I have a weighted GPA of 4.56, rank 11 out of 109 in my class, have tons of community service in, am in National Honor Society, and I got a 21 on my ACT (I’m going to retake it because I got a 28 on the practice test, so I know I can do better).

Do I have a good chance of admission?

You have a good chance, yes.