So for the last 3 tanks I've gotten worse mpg, 2 or more. Calculated, the mpg gauge is 3 or 4 optimistic anyway. I drive exactly the same, buy the same 93 octane at the same place. Stock 2018,no mods other than a K&N panel in the box and Nameless muffler deletes, both have been on for 5000 miles or so. I can also hear the turbo more, pronounced sucking air sound, which is cool but wondering why now and not before. Car has 11500 miles. No check engine light and no codes so I don't think there's a vacuum or boost leak, and everything is visually fine. Any thoughts?