2001-2016 Duramax S400 3.5" Stainless Steel Downpipe
Built to order — not a shelf part
Current build & coat time: 4–14 business days
Every Felder Kustom Fabrication part is fabricated after your order is placed, so lead times run longer than off-the-shelf parts. Lead time varies with our current build queue — contact us before ordering if you need an exact date.
The FKF 3.5" Stainless Steel S400 Duramax Downpipe is a fully mandrel-bent 304 stainless downpipe for 2001-2016 Duramax trucks running an S400-frame charger on a 6.5" tall pedestal. It bolts directly to your factory race pipe with no cutting, and unlike most S400 downpipes it does not come dented and does not need to be dented.
Features
- 304 3.5" stainless steel construction
- Billet stainless 4.62" (117mm) half marmon T4-style flange with clamp — fits Borg Warner S400 and Garrett G-Series 42 and 45
- Billet stainless lower downpipe flange — no cutting required, bolts directly to your factory race pipe
- TIG welded and back purged for strength and appearance
- Designed to work with 6.5" tall pedestals
- Does not come dented and does not need denting, with the exception of extended length up pipes
Fitment
2001-2016 GM 2500HD / 3500HD trucks with the 6.6L Duramax (LB7, LLY, LBZ, LMM, LML) running an S400-frame turbocharger on a 6.5" tall pedestal.
Flange compatibility: Borg Warner S400, Garrett G-Series 42 and 45. Note that S200 and S300 turbine discharge flanges are 4.25" marmon — close to the S400 T4 4.62" but they will not clamp together. Measure before ordering.
Frequently asked questions
What is the lead time on this downpipe?
Please allow 4-14 business days for build time. This downpipe is built to order, not pulled from a shelf. Contact us before ordering if you need an exact date.
Do I have to cut my exhaust to fit it?
No. The billet stainless lower flange bolts directly to your factory race pipe with no cutting required.
Does this downpipe need to be dented for clearance?
No. It does not come dented and does not need to be dented, with the exception of installs running extended length up pipes.
What turbo flange does it use?
A billet stainless 4.62" (117mm) half marmon T4-style flange, which fits Borg Warner S400 and Garrett G-Series 42 and 45 turbochargers. A clamp is included.
Will it work with a pedestal other than 6.5"?
This downpipe is designed around a 6.5" tall pedestal. Fitment on other pedestal heights is not guaranteed.