LB7/LLY/LBZ/LMM Duramax S400 3" Down Pipe 

S400 single-turbo Duramax builds need a half-marmon 3" down pipe off a T4 pedestal — OEM crushed pipes and S300 HX40 flanges will not mate. Wehrli’s combined WCF100878 / WCF100811 listing is the current WCFab S400 piece.

This part (WCF100878 / WCF100811): LB7 / LLY / LBZ / LMM / LML 6.6L Duramax 3" down pipe for S400 turbo with 4.6" diameter flat exhaust outlet flange (half marmon), V-band clamp, heat wrap, and high-temp coating. Mates to the exhaust system V-band with the OEM clamp. Must be used with a T4 pedestal between 5.5–6.5" tall. For LB7 use WCF100878; for LLY/LBZ/LMM/LML use WCF100811. Supersedes WCF100244.

Fitment gates:

• Fits Chevrolet / GMC 6.6L Duramax LB7 through LML with an S400 single turbo on a 5.5–6.5" T4 pedestal
• Not an S300 HX40-flange down pipe (WCF100122 / WCF100123)
• Not an OEM / drop-in IHI turbo down pipe (WCF100119 / 120 / 121 and stainless siblings)
• Not an L5P DOC-outlet 3.5" down pipe (WCF100129)
• Made in USA · Idaho Falls install help available when bay time allows

Shipping: This product cannot ship to California (same restriction as WCFab). WCFab lists in-stock with typical 3–5 business day ship. Free ground over $150 excludes HI/AK.

Call 208-542-7793 with year/engine/turbo/pedestal before you order so we pull the correct LB7 vs LLY+ SKU.

Emissions-compliant performance only — Powertech Diesel does not sell deletes or defeat devices. Keep required emissions equipment where legally required.