No matter, the intake will be the temperature of the air that is inducted. I've done extensive dyno tests on two Civics, and on long drives (ie, Vegas to Cali) the Iceman Civic and AEM Civic will both have cool intake arms when driven at night. On a hot day, both intake arms will be warm/hot and about the same temp.

Last thing to consider...the air won't even be in the intake long enough to get heated...so basically, there is no significant/discernible performance difference, all things equal.