A performance torque converter is highly specialized based on the performance characteristics of the specific vehicle. Sonnax has several levels of kits to ensure the best combination of performance and value for each application. These patented, powerhouse kits can be built in a variety of stall speeds, and offer fast, easy assembly with predictable tuning adjustments.

Sonnax JMBX performance converter kit GM-RK-688 for GM 6L80, 6L90 (258mm) applications delivers the performance characteristics of a high-stall with maximum lockup capacity.

Designed from the ground up to outperform OE and other aftermarket components, other kits that utilize GM 245mm or 265mm core are available.

• Fits 10.750", 11.062" and 11.500" flexplate bolt patterns
• Extra-thick piston resists bending and flexing under all extreme applications
• Heat-treated piston splines hold up under extreme lockup pressure
• Chromoly steel turbine/impeller hubs plus a fully-machined forged front cover provide superior strength and durability
• Build in a variety of stall speeds
• Fast, easy assembly with predictable tuning adjustments