A method and system for performing sheet registration are disclosed. A magnetized engine component establishes a magnetic field that varies in response to stress imparted within the engine. An ECU performs feedback control of the amount of fuel based on output of the air-fuel ratio sensor such that the engine air-fuel ratio seeks a stoichiometric air-fuel ratio. Also, a substrate processing system comprising that includes a processor to calculate a value for the process parameter to achieve a substantially uniform epitaxial layer of a target thickness on the substrate, where the value is calculated using a gain curve derived from measurements of layer uniformity as a function of the value of the process parameter.