Product Description
Unlock flow and lower EGTs on your LML with the MBRP GM8427 3" Turbo Down Pipe. This aluminized-steel turbo direct pipe replaces the restrictive factory unit to improve response and sound while retaining factory emissions hardware.
- Aluminized steel construction
- 3" turbo down pipe (direct pipe)
- Improves flow and heat retention
- Works with factory emissions equipment (DPF/DEF remains in place)
- Gain claims up to +21 HP / +24 lb-ft
Fitment
2011–2015 Chevrolet Silverado 2500HD/3500HD & GMC Sierra 2500HD/3500HD with 6.6L Duramax LML.
Note: Some 2015 LML trucks use a 3-bolt flange turbo direct pipe. This GM8427 model is for V-band style—verify before ordering.
Cross-Reference / Alternatives (MBRP-only)
- CARB-Compliant Alternative: MBRP GMCA427 3" Turbo Down Pipe (CARB EO D-763-2)
Recommended MBRP Pairings (DPF-/Filter-Back)
- MBRP S6032AL 4" Filter-Back, Single Side (Aluminized)
- MBRP S6032304 4" Filter-Back, Single Side (T304 Stainless)
- MBRP S6032BLK 4" Filter-Back, Single Side (Black Coated)
What’s Included
- 3" turbo down pipe (GM8427)
- Reuses factory mounting hardware/clamps where applicable
Helpful Notes
- Direct-fit; no tuning required.
- If your 2015 LML has a 3-bolt flange at the cat connection, this pipe will not fit—confirm before purchase.
FAQ
Is the GM8427 emissions-compliant and does it keep my DPF/DEF?Yes—this down pipe does not delete emissions components and retains DPF/DEF systems. For California/CARB usage, choose the GMCA427 (CARB EO D-763-2).
Will this fit my 2015 LML?
Many do, but some 2015s use a 3-bolt flange turbo direct pipe which is not compatible with GM8427. Check your flange style before ordering.
Do I need custom tuning after install?
No. This is a bolt-on component that does not require tuning.
What material is GM8427 made from?
Aluminized steel.
What kind of performance gains can I expect?
MBRP advertises improvements in flow, heat retention, sound, and published gains up to +21 HP and +24 lb-ft. Results vary by vehicle condition.
