Gonna Buy a 2nd Pheonix and have some questions

[grantlshiell]

Hello,

I picked up a 2002 Excursion with the 7.3 for my wife to drive. After about 1000km i fugured its getting 13.8 mpg which id really like to improve. I already have a pheonix in my 96 and would like to buy another one.
Could you tell me which tune would be the absolutely best for mileage not considering hp and could a custom tune be done that would be even better for mileage in this truck and what can i expect at best. I will also be getting hp tunes. the truck has intake and exhaust already.
Is the gryphon cts for this vehicle switch on the fly? and is the tuning itself different with a gryphon or the same as what i would get in a pheonix. thanks