I did it and it did make a difference...in sound and performance.
I had a CAF coming out of the left fog-light, removed the acoustic valve and had the CAF sealed all the way upto a Viper (closed induction kit)
I also did a test on the standard airbox, the viper without CAF and the viper with a CAF and the inlet temps on the final product were miles lower, something like 10 degrees C at various speeds. That can only mean power. However whatever you do short of cams won't make a big difference on the clio's.