That's more than likley the IAT(Intake Air Temp) Sensor. These engines do not use MAP sensors. They use a MAF instead. Cars ECUs generally use either/or to calculate fuel/air ratio. The IAT sensor is another, additional sensor used by the ECU for various other calculations...
If you plan to fit a tall FMIC core... although it seems there is a lot of space there with the bonnet open you will have to consider the bonnet catch which actually sits in a lot of the space you see with the bonnet open. It would foul on a tall core... which is why nobody actually makes a tall core for these cars.
*EDIT* In answer to your question about core size... 40mm seems to be the thickest you can use without cutting the bumper carrier etc... up to you of course. I think it's possible to fit 3" in there with some trimming, which in my opinion would be well worth it for the gains. Heaight x Width? Just measure it!