You'll get a different flavour using the small green calamansi limes, the medium size green limes or the thai limes -- anything outside of the regular yellow lemons I mean.
When you make your sugar syrup, boil it with a pandan leaf as well for a subtle aroma.
Use equal parts of freshly squeezed juice with sugar syrup, add about 6 parts of water and ice, and adjust accordingly to taste. That'll do it.
