fwiw (shades of rogue trader),
I find trading SGXNK much easier if simultaneously watching the prints in Japan (OSE) as well.
it's not quite "arb'able" but one can often give a heads up to the other. OSE has a 10 pt spread. SGX, a 5 pt spread. by watching the order flow on OSE, you can also get a bit of a headstart on a directional change, and/or help in getting filled on bid/ask.
just my experience.
i watch time/sales on both exchanges, but only chart the SGX.