lol, The best advice I can give you is don't drop from 2u, you can easily achieve a band 6 in 2u, a mark of say 70 in 2u maths is much better than a 90 in general maths.
If you can get a band 6 in 2u and band 5 in all you other subs, than that would get you 80 atar. 2u scales better than general, lol