@UCBUSCalum This may be of interest to you. I have not kept up with research, but looking at your post remembered reading this five to ten years ago and thinking it is very, very interesting. This research is from UC data.
From the Conclusion (FGPA is freshman GPA):
“The results presented here indicate that SAT scores are substantially more predictive of
eventual student performance across high schools than within. In other words, the average SAT
score at a student’s school is substantially more informative about that student’s eventual FGPA
than is the student’s own score.”
“Whether this would represent desirable policy depends on one’s view about the appropriate
role of school demographic characteristics in admissions decisions. A non-trivial portion of the
SAT’s across-school predictive power is due to its association with the school racial composition”
https://eml.berkeley.edu/~jrothst/restingpapers/satpaper2_june2009.pdf