Getting into top-tier Universities

I am currently a student studying Hong Kong, and I wish to study in schools like MIT.
But in Hong Kong it is extremely difficult to achieve a high GPA (atleast for me). So
Is it possible for me to be accepted by the top-tier schools? Is it possible if I have perfect
SAT scores and a lot of extracurricular activities?

They are aware of the grading system of different countries. So if a 70/100 is excellent in your grading system for instance, they will know that and evaluate your GPA differently.