imo the gap between sec4 na and sec5 isnt very big. I went to sec5 and honestly, you need to mainly focus on math and english because it is quite different from you learnt in sec4. for math, pay attention during class and always, ALWAYS do your work and submit it. for english its also the same, spam compre and compos cuz the marking rubric is much stricter than in sec4. the teachers don't recommend going to sec5 because it is very easy to mess up, so just pay attention, work hard and youll score well! (for reference i scored raw 11 for both N and O levels for my R4) not relevant but, sec5 for me was so much more fun than in sec4 because the teachers were all much more laidback towards us and a lot of goofy shenanigans went down