Hey guys looking to increase some fuel efficiency and some horsepower for my 06 h3. Not looking to making it a racecar, but want to make better than what I have now. I have asked around and some have said turbo charger, supercharger, cat back exhaust, and so forth. Would love some ideas to improve what I have now.

 

Your best bet is to drive with efficiency in mind and stay out of the skinny pedal. Low rolling resistance tires with proper air pressure. Tune up would possibly help if this has not been done recently.
MAF, TB cleaning. New sparkplugs AC Del 41-103. Fresh air filter. Drop any extra cr@p your not using daily, I.e. tools, extra gear, spare parts, heavy armor, spare tire etc.

IMHO these are just some of the least costly most mpg saving options realistically available.
Happy Hummer ing....

 

There is no turbo or supercharger available for the H3 that I'm aware of, and any exhaust will give only minor improvements (if at all). Tune-up, Air-Doc, keep your tires fully inflated...about all you can really do. If you wanted horsepower and efficiency, you shouldn't have bought a heavy non-aerodynamic full-time 4wd brick with a relatively small 5-cylinder engine.

 

Here is the list. Intake, Cat Back Exhaust, TB Port Polish, PCM tune with Efan conversion.

If you are even thinking of Turbo or Super Charging, you forgot that we are talking about a heavy off road vehicle, trying to high rev a I5 for pavement pounding is not really what yiu want to do.