The upper limit of the middle-50% range, as well as the lower limit, would go up after attrition. I think you can assume no meaningful difference in the stat profiles of the graduating classes. Follow your gut. If the weeder classes worry you, put the money you’d be saving aside and find a great math/physics tutor on Wyzant, and work with them from day one so that you don’t have to scramble to find help when you bump up against something hard. Join the clubs you’re excited about, form study groups with the other serious engineering students, and you will be fine.