biology 89% 1 or 2/25
business studies 90% 1 or 2/13
english adv 82% 3/23
chemistry 87% 2/15
math2u 87% 3/15
maths3u 70% 1/5
SOR 2unit 92% 1 or 2/20
Well, you see, it really depends on what you like and don't like. I personally, wouldn't drop 3U for several reasons such as this, it you do 3U, you will find 2U to be much easier to grasp and understand results in your 2U marks to be much higher and this is a big advantage of doing higher level Maths (3U). Assuming it doesn't burn a hole in your time, there's really not much reason to drop it and the great alignment and scaling is a further bonus. You are doing afew subjects that have rather poor scaling such as Business which 3U might even out scale if you got a lower mark.
Anyway, you have a decent change at hitting E4 and almost definately E3 the way you're going. I'm at a rank ~30 school and have about 70% average rank 24/65 or so where I may or may not get E4. Bottom line is that it is probably best to keep MX1 for now but if it causes that much trouble then it might be a possibility to drop but it is typically more beneficial to not drop MX1 in my opinion.
I know I have gone around in afew circles but I think you understand my point. I was just typing as thing popped into my mind.