MuddyRhino here,
2000 Blazer 2dr 4wd 4.3L V6....
I get around 11 mpg city, don't know about hwy yet...but its killing me in gas. What are some basic performance mods I can do to up my mpg? I heard swapping out the stock cold air intake would help, and exhaust system work, but does that really help?
Any answer is much appreciated.
thanks all

 

I have yet to find a "miracle mod" that gains any significant improvement in gas mileage. However, your blazer came from the factory getting 15-18 mpg city. I would search tune up and maintenance to restore your mileage back to factory specs.
Start simple. Are your tires stock size and properly inflated? Ignition (plugs,wires,cap & rotor) tuned up? Clean air and fuel Filters? Up to date on all fluid changes? Condition of the brakes, dragging, caliper seized? 4wd operating correctly. Vacuum leaks, evap and egr systems, check engine light. It all adds up.