I have seen people say the have lost fuel economy removing the stock air box. I purchased the Calmini and found the fitment poor and cost expensive. I would recommend Mike Morgans intake. He has posted on here a few times. I am getting one as soon as I get the coin together. As for the fuel economy I believe the increase in air adjusting fuel mixture higher. Secondly (hypothesis) the air box creates an ideal pressure effect. Yes, you get more performance but you also use more fuel. Pull the snorkel out, for starter, I would recommend to use your power button, keep your pressures on your tires to the top of the recommended spec (29psi) and go easy with the pedal mashing. If the clamini doesn't go in get a K&N fillter but don't over oil it....I am sure others will chime in. Good Luck