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 .