Vehicles equipped with 09G,09K,09M, 6F21WA, TF60SN transmissions often develop erratic or high line pressure due to excessive wear in the OE pressure regulator valve bore and/or boost valve and sleeve. This wear allows critical oil loss, preventing proper line pressure regulation. Without correct balance oil pressure, the PR valve will be out of its desired position, resulting in line pressure instability and possibly restricting cooler and lube flow to the secondary regulator valve. A deteriorated bore can cause lowered line pressure, resulting in soft shifting and burnt clutches. Reconditioning the bore and installing Sonnax oversized pressure regulator valve and boost valve kit 15741-01K restores proper line pressure and cooler flow. Contents Pressure Regulator Valve Pressure Regulator Spring Boost Sleeve Boost Valve