hahahaha...your sig!!
Keep in mind though that Yr 11 is a great year to have as many subjects and units as possible, because if you want to do the course in Yr 12, you will need to have done the Yr 11 course.
Eg. My prelim year, I had Modern History, 3 Units of English, Economics, Business (accelerated), Chemistry and 3 Units of Maths.
I mean thats 14 units and 6 distinct areas and subjects too. As I got to Yr 12, and was able to do a Distinction course (Philosophy), and could take on EE2 and Hist X, (ie. ADDING 4 previously unavailable units to make 16), I had to cull a few - so goodbye to economics and chemistry.
The other good thing about extension subjects is that you can drop things one unit at a time - this is abit safer than being stuck with a subject you don't like, but potetially if you drop it, its under 9 units - so you physically can't drop it.