Atune can make a big difference.
Our SRT got 21 MPG when we bought it last January. After Eurocharged De-tuned it for Cathy's driving style we get about 26.5 highway. Still rubs rubber off the rears tires when I want it too.
The NA went from 27.5 to 29.5 highway, this with bigger injectors installed and a tune.
Both of these numbers achieved on our St Louis to Dallas and back trip last week. At the pump together she added about 1/2 gal more to fill her tank than me on around 12 gallon fillups. Did that at least five times on the trip so I'm comfortable with the data.
Tighed, sounds like you need to get two tunes.
roadster with a stick