I don't think your going to come anywhere close to maxing out the fuel delivery abilities of the fuel system with just an intake, I'm like 99.99999999999% sure of that as Mazda would have had to specced it so the fuel pump and injectros run at or close to 100% of their rated duty cycle stock.
The issuse is, as far a I can tlell, making sure your MAFS (Mass Air Flow Sensor) is accurately reading the amount of air the intake is funneling to the engine. The problem with the Injen is that the MAFS thinks there is less airflow than there actually is and the ECU, given bad information, fails to send enough fuel for the actual air charge. The result is a lean burn that the 02 sensors detect which sets off a CEL .
If one were to hav a MAFS that is calibrated and/or designed for the Injen intake, and fed the ECU accurate data there would be no CEL issue at all.