Some advice...
(first)
I spoke with a friend regarding this "mod" He is a master tech with all the latest certs. He says the mass airflow sensor will see the increase in the volume of air and compensate with additional fuel resulting in a decrease in mpg. Additionally I asked about installing a K&N, he recommended against it as the same situation applies and also there is evidence that the oil residue from this type of filter is causing oxygen sensors to fail early. Looks like these damn cars are just too smart ! No easy way to coax extra performance unless you are willing to mess with the programming and sensors. BTW, my wife loves her CX, I have had precious few chances to drive it but when I do it is a blast.