Engine popping.
I just installed a short ram air intake in my car. I drove it around my friends block then i went back to his house and watched a movie. After that I drove back home, which is about a 45 minute drive. When I got home and turned my Engine off I notices a hallow metallic popping noise every few seconds or so, sometimes a shorter interval than that. It sounded like it was coming from the Exaust manifold, or that general area, any idea what it might be, or if I should be worried about it? I mean it sounds like it might be just cooling down, but it was loud and I never noticed it before.