I have no mods whatsoever. The drop in was it. After a week I took it out. I have tracked my MPG's closely since I bought the car, 80% of my driving is highway driving. It was easy to notice the rough idle and MPG's drop. I am pretty sure it was the filter since it was the only thing I changed. AEM told me over the phone each car is different and they did not believe a car needed to be tuned to use their filter. They didn't say it "didn't" just that they "did not believe" it did. So if anyone wants a drop in, it is theirs lol
You gotta check you didnt leave anything out of place, that issue isnt because the filter, it sounds more like hose off (vacuum/boost leak)