I would advise against ignoring/flunking your SACs though.
Asides from examples where you deserve about 50 (rargh's post is accurate, it is possible to not be the best and get 50), your sac mark can and will bring you down. It is much better to be the other way around and be #1 in SACs and stuff up the exam slightly.
Example: I (am pretty sure I) was rank 1 in methods, I lost 5 marks over both exams and got 43
Someone else from my class was near the bottom of the sac rankings, lost 4 marks over both exams and got 40. He bought a statement of marks, I know a little summary of my scores due to VCAA originally giving me 42 for it, so these are true numbers not 'oh I think I lost 4 marks when I really lost 10'
Example 2: My GAs for chinese were B+, A, A+ (GA 1 and 2 are sacs). High exam result doesn't pull them up. I got 34 and I know of people who got A in the exam component that got 36.