But if the cohort is bad, and I get 90s doesn't that mean I get EXTRA marks? ugh, so confusing.
And you're from MPSC? OMG!! Haha, first mpsc student I've seen on here. Private message me telling me your name?
Also, I'm already doing economics (in year 10) there's only one class and it's only got 12 people in it.

In 2010, no one at MPSC scored 40 or over in BM. You don't get "extra marks" for being near rank 1; I'm pretty sure all it means is your sacs won't be moderated negatively. The other problem with BM is its scaling makes it a bitch to have in the top 4. These 'easier subjects' don't guarantee good scores at all. In fact, it's harder to do well since the course is so easy and most people achieve well, hence more competition. Throw in scaling if you for some reason fall < 40, and then it's GG VCE if BM is in the top 4.
Who's your teacher for Economics?