Ive no idea mate to be honest. But if youve reset the ecu then it will have to learn all over again, and if it senses that theres a lot more air going in (which there will be cos of the induction kit), then surely it will compensate for this by increasing the amount of fuel? Otherwise it would be running too lean. Plus as tg says, it could be that your driving it faster. Seriously think about it, if your giving it a bit extra to hear the extra induction noise then this will explain the hike in fuel consumption too.