A Calibrated Air Intake Tract for Internal Combustion Engine is disclosed. The intake includes a Mass Airflow Sensor section that defines an inner diameter that differs from the diameter of the overall intake air tract piping. The Mass Airflow Sensor length and diameter are precision-tuned in order to provide the best engine performance without the typical “check engine” light being lit due to faulty mass airflow sensor readings. In those vehicles where necessary, an insert of the appropriate size and in the proper location is added to the interior wall of the MAFS section in order to correct final fuel trim level inadequacies.