Don't see people do software development very often.
If you are in an average cohort, you should almost certainly try to keep rank 1 for a chance for 45+. The SAT will consume a lot of your personal time, so please stick to schedules and due dates. Don't expect to do well just because you are good at coding, theory is equally as important.
The exam is also very hit or miss. I feel like I got very lucky this year, because Section C (the case study) was very weird, unlike 2016/2017 one where you had to refer to the case study, I didn't refer to the case study and pulled a 49
Be familiar with how to respond to questions in the exam, and what the examiner would want for the specific amount of marks. If you have a good teacher they will teach you this well, but otherwise refer to previous examination reports and understand the mark allocations.
Actual numbers:
SAC grades: high 90's rank 1,2 (pretty easy if you can code)
SAT grades: 80s - 90s should spend time perfecting and understanding the theory component (SRS)
Exam grades: 85+? i personally found it very hard to know whether the way i answered questions was right