I cut a chunk of the plastic guard off for easy access to the filter and to allow more cold air to enter the filter. Besides getting a bit ditier on one side, I see no problems at all. If it rains, the exposed side of the filter gets wet, but hey, it's an unoiled filter and AEM test-blasted their filters with dirt, water, and everything else that could be hitting it and the filters continued to keep all the junk out.
I wouldn't worry at all.

 

i got a kit IDENTICAL to yours, black and everything, and i know exactly the squeeling noise you are talking about. i have no idea what the noise is either and was wondering the same thing. if anyone could help us, that would be awesome.

 

You don't actually need to take your bumper off btw. I didn't with my install, and i also didn't cut anything out either. If you're cutting something you're doing it wrong.

 

They just cut so that they could have easier access to the filter

 

And taking your bumper off ususally helps a bit