I bought this PRO-M 80 MM from a guy off Turbostangs.com. I knew this had a ding it in from the picture he did take so he wasnt hiding it. I know its prob nothing at all I guess Im just looking for some reassurance.
The damaged place is such a small percentage I don't see how it would effect air flow.
I'd be more concerned about if it filtered correctly. Looks like the filter material is still intact from the picture. Just check to make sure everything is ok and use it if your comfortable with it.
Then I too, have sin from unrighteous modding in this area of my Mustang combo life.
Even though I made a hole in my fender big as some of those Northern States......I've seen the same kind of thing as in your pic on my filter which tells me I need to remove just a tad more material next to that spot