I DEMAND you look here. Ok, I strongly suggest it. These guys have it DOWN on tweaking CAI's in ways the big brands don't seem to. I put on on my Cobra, and as soon as I stated it I could 'feel' a difference in the car's attitude. It was as if it woke it up. Before going big bucks and down time in cams for mileage, maybe invest in a tuner instead. It can get you a little mpg, but you can flash it back to stock or even a little additional performance when you want it. I had an SCT tuner for the Cobra as well. And while not really giving me too much more HP, it did give me the ability to check codes and wipe them if needed. (My MAC Performance long tubes and high performance cats & exhaust screwed with the O2 sensors, and had to basically shut them off). But it also allowed me to make many different tuning options. I had to reset the idle for the CAI made it idle a little higher from just the additional air. I wish these guys made CAI's for standard Focus' rather than just the ST. I'd have one if they did.