I haven't really noticed any changes in the fuel economy. I've been stepping on it til 5.5k for so much just enjoying it that I've burned a lot. With an intake your fuel economy gets worse. As for performance, not really a huge gain, but a gain nonetheless. I felt my car just wanting to rev higher.
Installation wise, there were a few bumps here n there, but I improvised.
(1) taking out the clip on the MAF sensor, there is a little green tab that actually has an arrow pointing inwards. Push the green tab adn pull, the MAF sensor comes right out. (2) I used the gold plate that is attached to the top of the stock airbox to attach to the cone filter and then the intake tubing on the car itself. There are two nubs holding it in. Get a flathead and a hammer and try to hammer it out. You will crack your airbox a bit, but then you really won't want it back afterwards.
but going back to my original question. Does anyone know obvious signs of air leakage? shoudl I be getting a CEL by now?