Wehrli 01-04 Chevrolet 6.6L LB7 Duramax S400 Twin Turbo Kit (No Turbo) - WCFab Red

This Wehrli Custom Fabrication twin turbo kit is designed for the 2001-2004 Chevrolet Silverado 2500 HD and 3500, as well as the GMC Sierra 2500 HD and 3500, all equipped with the 6.6L LB7 Duramax engine. This kit is built to support an S400 series turbocharger and your stock IHI turbo, allowing for significant horsepower gains up to 1000 RWHP, depending on your chosen turbo and fuel system upgrades. It's a solid option for daily drivers and tow rigs that need more power, better fuel economy, and improved exhaust gas temperature (EGT) control, all while maintaining a turbo spool similar to stock.

When you open the box, you'll find everything needed to get your compound turbo setup installed, including a coolant overflow tank with all its hoses and fittings, a low coolant sensor, silicone boots, and various clamps. It also comes with an atmosphere turbo pedestal that has a built-in oil return fitting, a 5-inch intake with a dry air filter and Outerwears pre-filter cover, and stainless steel oil feed and drain lines. You also get a 3.5-inch cold side charge pipe, a 3-inch one-piece Y-bridge with a heavy-duty bead roll, and a 4-inch ceramic-coated turbo downpipe. The kit is finished off with a durable custom red powder coat for a clean look.

Wehrli recommends specific turbocharger combinations to achieve your desired performance. For up to 750 RWHP with the best turbo spool, an S475 turbo paired with the stock IHI is a popular choice, especially if you're running stock fuel systems. If you're looking for more top-end power, an S480 turbo can get you to 800+ RWHP, though it might sacrifice a bit of low-end spool. For over 900 RWHP, an S480 paired with a 64mm drop-in turbo offers improved top-end performance with moderate spool characteristics. For any of these higher horsepower setups, Wehrli recommends a built Allison transmission to handle the increased power.