When the balance spool bore in Mazda G4FA-EL units wears, the valve won't stroke to regulate EPC pressure. If the middle spool bore wears, line pressure will be allowed to exhaust. Sonnax oversized pressure modifier valve 74846-04 restores hydraulic integrity to the circuit by sealing these locations in the bore. It is highly recommended that the pressure regulator bore also be checked for wear. A worn pressure regulator bore can result in low/high line pressure, harsh shifts, lack of cooler flow, and/or blued converters. Sonnax offers an oversized pressure regulator valve 74846-05 to restore the integrity of a worn pressure regulator bore. Valve is manufactured from anodized aluminum for improved wear resistance OE spring can be reused thanks to shortened spring seat depth that compensates for the oversized valve