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

This Wehrli Custom Fabrication twin turbo kit is built around a 4-inch ceramic-coated stainless steel downpipe, designed to handle the increased exhaust flow from a compound turbo setup on your 2001-2004 Duramax LB7. It's engineered to work with an S400-style atmospheric turbo and your truck's stock IHI turbo, creating a compound system that can support up to 1000 rear-wheel horsepower with the right supporting modifications. This kit is a solid option for daily drivers and tow rigs that need more power, better fuel economy, and improved exhaust gas temperature control, all while maintaining a turbo spool that feels similar to stock.

Wehrli includes everything you need to get this compound setup installed, minus the actual turbos. You'll find silicone boots, T-bolt clamps, and V-band clamps for secure connections, along with heat wrap and clamps to manage exhaust temperatures. The kit also comes with a coolant overflow tank, complete with hoses, fittings, and a low coolant sensor, plus a custom powder-coated atmosphere turbo pedestal that has a built-in oil return fitting. For intake and exhaust plumbing, you get a 5-inch dry air filter with an Outerwears pre-filter cover, stainless steel oil feed and drain lines, a 3.5-inch cold side charge pipe, a 3.5-inch turbo inlet horn, a one-piece 3-inch Y-bridge with a heavy-duty bead roll end, and a 3-inch cold side intercooler pipe. The Bengal Silver finish adds a custom look to your engine bay.

When choosing your turbos, Wehrli recommends specific combinations for different power goals. An S475 over the stock IHI turbo is a popular choice for up to 750 RWHP with good spool characteristics, especially on stock fuel systems. If you're looking for more top-end power, an S480 over the stock IHI can support 800+ RWHP, though it might sacrifice a little low-end spool. For the highest power levels, an S480 over a 64mm drop-in turbo can achieve over 900 RWHP with moderate spool. For any of these setups, Wehrli recommends a built Allison transmission to handle the increased power.