Is AP US hard in High School Junior year?

I am in standard History now and I have never gotten lower than an 80 (except on the midterm) and I am currently getting an A- in the cl. I love to learn about history and I know that AP goes into more depth so that's why I want to take it. Anyways, I have never taken an AP cl and this year I am only in one honors cl )the rest cp1) So for anyone who has taken APUS in junior year of high school, how did it work out? Cuz I know Junior year is the hardest and most stressful year.