- You should be able to copy the files straight into you assetto corsa folder as long as you have the track installed. It will ask to override - backup your track if you want to keep the original files.
- If the new grass still won't show check your assetto corsa folder: extension/textures/grass_fx. You should have a "highlands.dds" file in there, otherwise no grassFX.
Don't think there's a real rally going on on the strada provinciale so I declared it as fictional track.
It's quite a high speed stage, broken up with a few chicanes.
Visually there's not much to improve the original look, it's Sicily so the ground is burnt by the sun,
lush green grass would not help much here.