I am going to be adding a 6” lift to my truck with 35” tires, i currently have 2.5” level kit in front and 3” in the rear with the equivalent of 34” tires and i get about 10.5 mpg. Anyone have thoughts about chips or performance boosters to get more horsepower to improve mpg’s with the lift and tires?

 

In my opinion, the best way to get what your looking for is a gear swap. If you're sticking with 35" tires, I'd go with 4.10 ratio and if you are even thinking about going with 37" I'd go with 4.56 ratio.
Here's a basic to get you started, but others will chime in with their thoughts as well. https://www.omix-ada.com/gear-ratio-vs-tire-size

 

Gears + tune is best option. Tune at minimum. 5-Star, MPT, Oz Tuning, etc. etc.