I have 07 with 5.9 looking to help out mileage.not towing much but if I do it will be boat(ski) or 3400lb car.

 

i think most will agree that intake and exhaust are a good start, pretty cheap too. then a chip or tuner. you can check out my sig, I am getting 25mpg combined city/hwy (hand calculated) with that setup.

 

Gauges first, then something else.

 

Guages are definately a first, then whatever you feel that you want. I just did the Diablo Puck/Predator stack and it is great. Have not run a tank yet but I will be sure to post my MPG when I get throught a tank or two.

 

yeah, those too. forgot to add that to the list. way to keep me honest

 

I'd do a free flowing muffler, then an intake, then gauges. Once that is done, bomb away.....

 

Gauges, exhaust, intake.

 

Muffler and intake can come first. They won't add that much power that you'd have to worry about. If anything the egts will be reduce slightly. Later when you want to add a chip, that would be the best time to add the gauges.
That was my order.