Actually that's a good thing you brought it up Scinery. I was also pressured into taking chemistry due to the whole "scaling myth" and it was the one subject that I really hated and didn't do that well in. It is also a testimony for year 10, 11 or year 12 students thinking of dropping a subject, that you SHOULD NOT base your subject selections upon scaling myths. They change every year and are unpredictable. If you do shit in the subject scaling won't work in your favour so there is no point. The thing you need to take away from this is, do something you enjoy because it is most likely that you will do well in it.
However, all hope is not lost for those who find that it is too late to right their wrongs and don't be discouraged by what I have just said. Put in the hard yards, try to enjoy the subject even if you may not be doing that well in the course due to specific reasons. I know that I spent the most time trying to improve my chemistry rank during year 12 and I still didn't get very promising results. Luckily, my other subjects were those I enjoyed greatly and had a talent in so it all worked out in the end. I managed to pull a band 6 in chemistry on the last run and so it is definitely possible for you to do well even if you have been lacking during the whole year.
Keep your head up and the HSC should be a breeze. I found that the biggest challenge during the HSC was not so much the content or academics but rather the psychology battle in my head with one side telling me that "I couldn't do it" and the other saying that "I could". If you can win the battle in your head, as weird as that sounds, you've already won the war
(This sounds really cheesy)
Good luck to all HSC'ers next year!