TransGo A1-LU-BST-04 Boost Valve | 2004.5-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Features:

• Reduces converter clutch apply pressure
• Lowers pressure spikes from 255 to 155 PSI
• Maintains line pressure up to 190 PSI
• Controls fluid flow for smoother shifting
• Helps prevent clutch slip and wear
• Improves shift feel and transmission life
• Designed for 2004.5-2010 6.6L Duramax
• Compatible with Allison 1000 transmissions
• Ideal for towing and performance builds
• No tuning or electronics required
• Precision-machined for reliable performance
• Easy upgrade for better drivability

Make Your Allison Transmission Shift Like It Should

If your Duramax doesn’t feel quite right when the torque converter clutch engages, the TransGo A1-LU-BST-04 Boost Valve is the upgrade you’ve been looking for. Whether you're towing heavy loads or just cruising around town, this valve smooths out those hard converter clutch engagements that can make your truck feel clunky and unrefined. It helps reduce excessive line pressure when the clutch applies, which means less stress on your transmission and a much more controlled shift experience. You’ll notice the difference in daily driving, fewer jerky shifts, less strain, and better drivability across the board. This is a smart choice if you want your truck to feel tighter, respond better, and last longer. The best part is, you don’t need to mess with any tuning or electronics to get the benefit. Just install it and enjoy a smoother ride that feels factory-tuned the way it should have been from the start.

Balance Line Pressure For Peak Transmission Performance

The TransGo A1-LU-BST-04 Boost Valve is designed to improve fluid control in the Allison 1000 transmission found in 2004.5-2010 GM 2500HD and 3500HD trucks with the 6.6L Duramax engine. During torque converter clutch apply, stock line pressure can reach around 255 PSI, which places unnecessary strain on internal components. This valve corrects that by dropping the pressure to around 155 PSI, helping to reduce wear and maintain consistent operation under load. Unlike some pressure mods that compromise performance, this one still allows main line pressure to reach up to 190 PSI when needed, preserving the transmission’s ability to handle torque under tough conditions. It’s a precisely engineered fix that improves how the converter clutch engages, resulting in smoother, more reliable shifts. The part is drop-in ready and requires no external tuning or programming. It’s a solid upgrade for anyone looking to fine-tune their transmission without overcomplicating things.

Fits: 2004.5, 2005, 2006, 2007, 2008, 2009, 2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Notes:

• Specifically designed for 2004.5-2010 GM 6.6L Duramax
• Fits Allison 1000 automatic transmissions
• Reduces converter clutch apply pressure to 155 PSI
• Allows main line pressure to remain up to 190 PSI
• Helps manage pressure spikes during clutch engagement
• Improves converter clutch control and shift quality
• Ideal for both stock and performance applications
• No tuning or electronic modifications required
• Installation involves accessing internal transmission components
• Not interchangeable with boost valves for earlier LB7 models