All Synthetic fluids in everything.
MSD Coil, much hotter more powerful spark.
New MSD Wires.
Cold air intake, DIY or name brand, just use K&N filter.
Headers & dual exhaust. I wrap my headers.
Remove engine fan & replace with dual electrical fans. gives more HP too.
I replaced bearings with best available for less rolling resistance.
I inflate my 285/75/16's to 48LBS and rotate every 4K.
Take out & clean injectors or have an injector cleaning done professionally.
Remove ALL extra & not needed weight.
Easy on gas pedal, manuals are better on gas.
Coast on hills, coming up to red lights/stop signs, IN Neutral.
I changed my 5.9 to a 5.2 & MPG is WAY better.
Use AC only if absolutely necessary.
I live in Rural area east of Toronto and have many times turned engine off and coasted down large hills for up to 7.5K or 4.5 miles.
MPG stays around 19-21 depending on how much I HyperMile
1998 Ram 1500 4x4