Why do I want to modify the grille?

To help provide a path for cooler air to be fed to the air intake. This will help to improve output power and reduce air intake temperatures, thus also helping to lower the chances of detonation

Okay, how do I modify the grille?

  Firstly the grille needs to be removed from the car. Remove the top 3 screws from the plastic upper part of the grille. In the lower part of the grille are some plastic catches, these have a small plastic lever that is pushed to one side to release the grille from the car. Pull the grille forward and remove the headlight washer pipe work from the grille
With the grille removed you can see the path that the cooler air will take
The removed grille
At the end of the grille the "plastic lattice" is blanked off. If the blanking is removed the air will travel into the air filter area much better
Drill the plastic where you want the ends of the slots...
...and take a hacksaw and remove the material between each hole. Once the material has been removed you might want to run over the area with a file to tidy things up
  Job done, simply refit grille!