The car could possibly run rich due to the intake only ingesting hot air. Where as with the factory intake & resonator, you'd be getting some what of cooler air flow. Assuming that the big resonator above the radiator, just under the hood actually pulls in cooler air from the front of the car. According to Jim Merderer, the test engineer that worked with the MP3, that was the main problem with the short ram intakes, they tweakout the sensor and give wierd signals to the ECU. I'm assuming we'd run rich, because that's the usual thing that happens with most cars I've dealt with.
Running rich isn't neccesarily bad, introduce more spark and you'll probably get more power.