I'm from N(A) too, but thats mainly because of my chinese which
screwed my psle score up royally. shesh.
I'm studying in JC now.
If you're in N(T) now, and you think you have the ability, i would
advise you to study for your O levels privately. Instead of going
to the ITE route. But if you think you dun wish to put yourself
through all that, then the ITE isnt too bad either.
Good luck! Study hard.