May I add to this post?
When I first bought my car (Civic Si 2006) I purchased an Injen CAI intake. I also have a ScanGuageII (It tells me the air intake temperatures, among other things). Recently I have gone back to the stock intake and here's what I've noticed....
The stock intake runs about 25 degrees hotter than the outside temp displayed on the dashboard.
The Injen CAI ran 15 degree hotter than the outside temp displayed on the dashboard. (My CAI was also wrapped with heat resistant/reflecting material)
I also ran my Civic Si with the stock air cleaner but without the added hoses before the air filter box. Then the air intake temp was always around 120-130 degrees on a 60-70 degree day (not good!).
Anyways, back to my original point. The stock Intake and the Injen both do their part in sucking in cooler air. Unfortunately the stock air intake has a lot more bends and piping for the air to go through. And unfortunately the Injen CAI is a pain in the arse to install and also to change the air filter.
I'm back on the original intake and I am loving it.
I hope this helps someone somewhere
-J