How big a step down are the CSUs vs the UCs

UC’s and CSU’s do not consider 9th grades in their GPA calculation, only 10-11th so until you complete Junior year, have a calculated capped weighted UC/CSU GPA and test scores, this post is moot. Cal Poly SLO is the exception which uses 9-11th grades in their GPA calculation.

In a couple of years when you actually apply, much may be changed regarding admission requirements. It is great you are doing research early but as a student you will grow in likes and dislikes so your college list may completely change.

Continue to do well in school, enjoy the next few years and come back when you are ready to apply.

Best of luck.