GMC Sierra Twin Turbo Kit - Wehrli - S400/Stock - Cat Yellow - 01-04. For 2001–2004 Duramax LB7 trucks, this compound kit adds an S400 atmosphere over the stock-location turbo for responsive power and control.

Built for daily-driven work and tow rigs, it supports higher horsepower potential, improved fuel mileage, and strong EGT management with near-stock spool. Suggested pairings: S475/stock (~750 RWHP), S480/stock (800+), or S480/64mm drop-in (900+), all with supporting mods; a built Allison is recommended. Not compatible with Banks intercoolers without additional parts and lead time. Passenger-side battery relocation required. Hot/driver-side intercooler pipe sold separately (WCF100349). Turbochargers not included.

Features

• 5" intake, dry air filter, Outerwears pre-filter
• 4" ceramic-coated downpipe
• 3" one-piece Y-bridge; 3.5" inlet horn; charge pipes
• Stainless oil feed/return lines; silicone boots; T-bolt and V-band clamps; heat wrap
• Coolant overflow tank with hoses, fittings, low-coolant sensor
• Durable Cat Yellow powder coat; Made in USA

Questions or planning an install? Call our Austin, TX or Los Angeles, CA area teams — we offer installation and customization at both shops: 512-982-9393 (TX), 562-981-6800 (CA).

Buying multiple items? Contact us for shipping discounts. We install on premises at both locations.

CA Residents: WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov