Heres my $0.02, after installing my CAI, I certainly noticed better throttle response at low rpm, and gained 1.8 mpg HWY. Now I have no legit numbers or scientific proof, just my experience. The mpg gain is HIGHWAY, and tested two 1500 km trips with stock intake and 3 1500km trips with the CAI. same load, same fuel, same route, same cruise setting and all within july-aug Albertan weather.
keep in mind that after I swapped intakes I reset the computer 3 times over a week of normal mixed driving to let the truck re-map for the different air flow, and it makes a huge difference.
Despite all the debate about different intakes not affecting MPG, I call BS, because I've seen the gains over and over again, but again its MY opinion and your all entitled to your own