More hp and mpg out of my 1999 dodge ram 1500 5.9

I am thinking about putting a superchip in it or ignition system. But I want to
get more hp with better mpg. Ive heard the super chip gives you hp and mpg.
I already have a new single exit flow master exhuast with 2.5in piping but
every thing else is stock in the truck and the tranny has been taken care of
and still works amazing