Vehicles with Ford C6 transmissions often display poor line rise, which results in erratic shift timing, Reverse shudder or direct clutch failure. This can be caused by excess wear at the inside diameter of the boost sleeve. This wear allows oil to leak past the boost valve to exhaust, resulting in poor or no line rise. Recover the hydraulic integrity of the boost circuit and restore proper line rise by installing Sonnax gas-ratio boost valve kit 36946-04K. Gas-ratio kit restores OE boost pressure Sleeve manufactured from highly wear-resistant aluminum Hardcoat anodized aluminum valve combats premature wear Drop-in Zip Valve™ parts install quickly and easily