I think every little bit counts. The mod could be done cheaply if you can get the pipe at a good price.
I remember reading in an article sometime ago that conveyed- for every 4 degrees colder the intake air is, you will gain around 1kw of power. Not that good really. However if you calculate the difference between the ambient tempreture and the tempreture under the bonnet of a car, I believe you could ultimately gain 5 kw or maybe more.
One has to remember that on a highly worked motor, cold air intake will almost certainly making tuning easier and ensure a more detonation resistant engine.