I'm just gonna
When you put the stock filter back in place, what do you do with that extra pipe that you cut out of the box? I was actually going to mention that the hole you've made in the box probably needs to be sealed around the pipe, which will make it harder for you to switch back to stock. The whole system would need to be under vacuum, and introducing that hole seems a little advantageous, IMO. I've seen MAFs scream for something as trivial as a greasy fingerprint on the sensor, so I can't imagine it not screaming about your setup. Seems like you have a vacuum leak somewhere. If you're just replacing the OEM filter for it to stop screaming, then it would seem that it might be a fitment issue with the new filter. Me personally, I wouldn't use the kind of setup you have unless I'm sure that I've covered all air leaks, and the filter is doing its job. If going OEM resolves your issue, I don't see Nissan trying to fix what essentially isn't broken.