Truck feels like it runs fine. Definitely more power, but around here driving stop light to stop light it barely averages 14. And since texas speed limits are 70-85 I'm usually doing 75-80 and my mileage stays around 15.
Now don't get me wrong, as long as this thing isn't doing any harm then it works just the way its intended to. And really if you're worried about mileage it'll unplug in 5 minutes for a long drive.