Not all cars run the same, but a general rule of thumb is you should be safe to drop down to a 3.5 pulley with CAI, 180* Thermostat, colder plugs (1 range colder is enough), and a good tune assuming you can run 93 octane fuel. Any lower octane and you are increasing your chance of pre-detonation.
Something else I would personally recommend if you plan to stay mild is the rocker upgrade. I've got modified 1.9 ratio rockers, the true 1.9:1 roller rockers are the best way to go. Either way, paired with the smaller pulley it gives you a very noticeable HP increase with minimal impact to cruising MPG.
Take a look here if you haven't already: What order should I MOD my engine