Thank you indigo, what a clear and detailed response !!
I do provide him extra work at home whenever he wants. He takes after-school math classes, and I am also thinking of enrolling in Singapore Math this year.
We do informal brain games and fun puzzles all the time. His school has a good math club that conducts tournaments a couple of times in a year. He is a good speller and participates in bee contests.
I am thinking I will go ahead with the testing , after all.

Thomas Percy, your reply made me feel much better. Thanks much. He does learn our traditional music and is into badminton at preliminary levels. He loves his taek won do training very much :-). He hates swimming, I just do not know why:-) I will look into other venues like JH CTY and try to do my best for him.