I just installed this on my 2012 JK and took it for a spin around the neighborhood--the enhanced acceleration is amazing! The stock intake must have really been sucking for air as the truck always seemed to hesitate a little taking off, but this modification makes it smooth and swift (plus gives you a slight throaty roar when you really hit the pedal!). Don't know about any fuel efficiency improvement but I'm already sold on the faster performance out of the gate. Only complaint is with the instructions: poorly written and overly complicated (and most of the pictures are too dark to decipher). They could have easily condensed the 19 or 20 steps into 10 from a clarity perspective, not to mention a more logical sequence that would save time. Fortunately there aren't too many parts, so even a weekend mechanic should be able to figure it out with the instructions as a rough guide. Highly recommend based on my initial experience.