I was doing some talking with some engineers at work and we could not come up with a consensus answer. My questions was this:

It is pretty well accepted that a CAI does not do much for power on a NA 996. When your car is at altitude (I'm in Boulder, CO) it loses power due to less oxygen in the air. Would our cars benefit more from a CAI up here than down at sea level?

I know that my car has lost power since moving here from Florida ad thought I would pose the question.

 

The cold air intake may help in power, but not any more in relation to if you were at sea level.

Your loss of power is because of reduced air density at your altitude, the cold air intake cant mitigate that.

Breathing mods will help regardless of altitude, but the car will make more power with those mods at a lower altitude.

 

If nothing else changes to the airflow and IF the CAI increases the amount of air to the intake or it reduces the tempertures of the air (increases density), by definition, you MUST have more power.

However, changing anything involving the intake can also change the velosity of the air which can either increase or decrease the VE of the engine and effect power accordingly.

However, as mentioned above, your problem is atmospheric pressure and short of boosting your intake air, there is nothing you can do to offset that loss.