Use the larger amount of curry paste if you like a stronger/spicier flavour, but keep in mind that adding more paste will also make it more salty, so you will have to reduce the fish sauce. If using store bought curry paste, I recommend using Mae Ploy, Namjai, or Aroy-D. If using Maesri or Thai Kitchen I recommend doubling the amount of paste. See my curry paste review for more details on the different brands.