A level is easier than stpm...getting 4As in A lvl does not mean that u can get 4.0 in stpm. And that is if you're the type tat is willing to sacrifice your sleeping time to get everything imprinted in your mind and diligent enough to finish all the past year papers as well as try your best to understand everything that seems incomprehensible to you. Its really not that hard...its all about the efforts that u put. Taking 3 subjects will make life easier for sure~ and its sufficient to enter uni with js 3 subjects. However taking 4 will give you higher chance to secure a place in highly prestigious universities like ANU, melbourne, sydney, UCL, NTU...the list goes on (also depending on what course u're applying larh).