not a daft question at all this. IC is 1 of the famous mods people do if u check cosies out at car shows.

bigger, or more efficient i should say, Intercoolers will bring your charge air temp down. cooler air means that you can get more air into your cylinders per revolution, which in turn to keep this plain and simple equals more power.

anyhow, since the air/fuel ratio changed more fuel is needed to compensate. the standard ecu is able to handle this change i am sure without the engine going up in a fireball .....
but a live map would really let you profit from the changes made and give you more driveability.

i would say not absolutely necessary but worth it

my 5 cents....