OMG he has a face!

You can always just take the cat out and look at it. Personally, I don't think that's the problem. Sounds like you're running too rich, which is what's contributing to the backfires. You need to check you timing, and make sure that all of your AEM intake couplings are tight. That's just a start. A used MAFS is ~$40. Nissan's don't have MAP sensors.

There should be a hose or 2 coming from the intake pipe near the throttle. Tell me where they go. It looks like there might be a problem there, but its hard to tell in the video.