To the OP, not normal your fuel economy is drastically decreased assuming same accelerator input. As some have suggested, either pull the negative terminal out of the battery to reset the ECU, or put back the original.
First, congrats! I have the Takeda intake (see Performance section) and I'm happy with it. I felt the slight gain in performance, but it's small. Sound is great about 3500 rpm but then you'll be wasting more fuel. No noticeable changes in MPGs before and after, when under the same driving conditions of course.
Bang for the buck is not good with an intake and if that's what you're looking for, you're better off spending a little more for an exhaust system, and one that is good value is the Magnaflow, either bolt-on or custom built. Mine was about $900 custom, but the bolt-on version can be had for a little cheaper. Intake and exhaust, combined have reduced my 250 AWD 0-60 times by 0.8 secs, at 7.45 sec.
Thanks for all the feed back guys! I have been driving it for a few weeks now and the MPGs have averaged out to what they were before I put the intake.. so thats a good thing.. probably how I was pushing it at the beginning.. along with the computer adjusting to the new air flow. I have noticed a little extra push from the intake, and I am happy with the sound, so overall was worth the $230 I spent for the intake