no point really unless the engine can really make use of them - more aggressive cams, ported and polished head, better exhaust headers and pipes, and an ECU remap, not to mention you may need a better fuel pump and definitely a new pressure regulator.
Plus only an injector change would mess up the fuel delivery and the car would likely run too rich.
Sorry mate, only a remap or engine work would really
help on a 1.6S. Even then the return on your money would not be very good - you'd be better off trading for a 1.8T.