Should I take the SAT subject test?

I’m a senior in high school, and I have taken the SAT twice. My highest score was a 1440. Since, at this point, my best opportunity to take any test would be October, I was wondering whether I should take the SAT subject test or the SAT. I’m currently aiming for schools like Johns Hopkins, Duke, and Northwestern, and I will most likely major in biomedical engineering. I also got a 4 in AP chem and a 5 in AP calc AB. In my position, would it be more beneficial to take the SAT subject test (on a math or science) and do well or take the SAT and improve by 50+ points? A lot of people say to take subject tests to show that you’re doing well in certain subjects, but I feel like that’s already shown in my AP scores and that focusing on improving my SAT score is a better investment. Who knows? I just want a second opinion on this.