Performance ratio with .531" & .492" dia. valve spools.

Vehicles with GM 5L40-E and 5L50-E transmissions are prone to poor line rise or high Reverse pressure problems causing poor shift quality and clutch failure due to leakage at the boost valve assembly. Sonnax offers two boost valve kits: the 55209-01K performance ratio (higher line rise and firmer shifts) and the OE ratio 55209-04K for factory performance.

• Hardcoat anodized aluminum valves combat premature wear
• Boost sleeves are made from alloy aluminum specifically designed to resist wear
• Increased performance ratio 55209-01K or OE ratio 55209-04K kits are available