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about the warm air intake. If the vehicle has a MAF, a more efficient flow of air to that MAF "cold air intake" will net a greater lb/min, gram/s or lambda based on AFR (whatever you personally measure MAF readings with from Hz). Measured target AFR will be 5-15% over the actual, meaning you'll be running slightly lean. If this lean event is not enough for the ECM to add enough fuel to noticeably effect long term fuel trims, you'll net slightly better mpg. The only way to change this is to tune the MAF tables while driving or on a load dyno.
This is how K&N and others can advertise a '3%' gas mileage increase or whatever we've seen out there. It isn't because the cold air is creating this efficiency, its the reduced constriction to the MAF from the design of a CAI. Mail order tunes are not going to be accurate to change this at all.
Most cars a few years older that are being used for super mpg use speed density, without a MAF. In which case warmer is better, to a point. Check to see what style tune you have on the ECM and go from there.
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