i've installed the AEM CAI
in my car. your talking about the 2-pice tube that connects to the radiator-thing and the ECU, right?
i was not able to fit the bottom piece into the hole again, because the CAI
blocks/takes up too much space. you dont need it anyways, no harm will be done, but if you feel unsure about that, then do what i did...i attached the pipes back onto the ECU and cut the bottom piece and made it at the same height as the radiator fans. that way air will still flow into it and even more air will enter once the fans start spinning.