So i installed this $60 Ebay no name intake a few months ago. CAI And i always wanted to seal it off from the engine bay, just never got around to it. Well my buddy was tuning it and told me if i got my IAT's down he could add a little more timing (idling for 20 minutes or so in the Texas heat with the A/C on full blast my IAT's were at 135*). So he suggested i seal off the air box. I did one better and made a crappy little scoop that gets fresh air from under the front bumper. Well i tried the idle for 20 min with A/C blasting test (outside temp was about the same) and my IAT's came down to about 115*. Even better is once i start moving they drop down to outside temp in a few seconds. Before at a stop light they would climb from 90* to about 117* then very slowly drop back down when i started moving. Now they climb from 90* to about 95* and drop back down to 90* in about 4 seconds after i start moving. I know it looks goofy but i don't care, it works.
All i used was some waxed cardboard i had laying around, flashing tape (you use this stuff to seal around doors and windows in your house) and some thermal barrier stuff. Spent like $20 total.