Originally Posted by JK-Ford

So you have made modifications to get more air and fuel through the system. But have not retuned the system to the new flow. And you wonder why your fuel econimy has suffered? You need to purchase a tuner to take advantage of your new flow without wasting fuel and energy. That is why they call it the BIG 3. Air, exhaust and tune.

Originally Posted by mike-d

But I have a MPG question. Now I know that a JKU is not the most economic vehicle out there and I have always been a Jeep guy, so here it goes. My JKU is getting about 15.2 MPG all city never gets on the highway pretty much stock. I have a AIRAID intake and flowmaster exhaust. that's it. I cant figure out why its so low. I just changed my diff fluid but and its been about 30 degrees here, I cant think of any reason why it is so low. Any hypothosis' on this. Thanks guys.