If you are a racer and have an LBZ-LML 6.6L Duramax, Gale Banks Engineering offers The best cast Duramax manifold ever. Lay the power down with Banks Big Hoss Duramax Exhaust Manifolds!
For high performance, getting the exhaust gasses out of an engine is just as important as getting air into it. These race-ready, high-flow manifolds were designed by Banks for the ultimate in fit and performance.
For use at sanctioned race events only
- Designed and perfected in computer simulations for maximum drive pressure
- CNC ported to fit aftermarket big port heads
- 1.77" x 1.58" Race Ported Inlet Ports
- 2.125" Race Ported Outlet Port
- Outlet Flanges sized for 2.25" .06 wall tubing
- Outlet Bolts M10x1.5 (not included)
- Banks' Precision Port Alignment System allows the manifold to expand & contract without shrouding ports
- Can be mounted stock position or reversed towards the front
- Proprietary bolt pattern on outlets for ease of bolt installatio, includes gaskets
- High silicon moly for extreme temps
- We recommend using ARP 762-1008 SS Hex M10x1.5 fasteners to the head (not included)
- Does NOT work with OEM or aftermarket up-pipes (Flanges included for fabrication of custom up-pipes)
Emissions Compliant: Race Only
Duramax Exhaust Manifolds Comparison

A) Port size 39mm wide x 35mm high, Area = 1,320mm2
B) Inadequate cross-section for high output
C) Poor entry conditions, No port runner blend to the main runner
D) Exhaust runner choke point
E) Exhaust port choke point
F) Outlet size diameter = 45mm, Area = 1,590mm2
E) Special high-temp material
Comments: Okay for lower power.
- Poor flow dynamics
- Unequal cylinder to cylinder back pressures
- Inlet & outlet undersized
- Up pipes are small & restrictive

A) Port size 37mm wide x 36mm high, Area = 1,295mm2
B) Inadequate cross-section for high output
C) Inadequate cross-section
D) Inadequate cross-section
E) Reverse flow
F) Outlet size diameter = 46mm, Area = 1,161mm2
Comments: Flawed & obsolete design
- Port size smaller than stock and not sufficient for high performance
- Rear port causes excessive turbulence
- Outlet smaller than stock
- Will not fit currently ported heads
- Up pipes restrictive & mild steel in bends

A) Port size 44mm wide x 35mm high, Area = 1,512mm2
B) Chokepoint, 19% smaller than the port inlet
C) Restriction/chokepoint
D) Chokepoint
E) Chokepoint
F) Choked port 16% smaller than the inlet port
G) Outlet size diameter = 48mm, Area = 1,832mm2
E) Special high-temp material
Comments: Very crude & obsolete
- Chokepoints cause inconsistent flow velocity reducing flow potential
- Ports not high enough or wide enough for current ported heads
- Up pipes restrictive and mild steel will fail quickly in any performance situation

A) Port size 45mm wide x 40mm high, Area = 1,745mm2 (Largest in industry)
B) Increasing streamlined cross-section
C) Consistent flow dynamics to port
D) Outlet size diameter = 54mm, Area = 2,290mm2 (Largest in industry)
E) Special high-temp material
Comments: The best cast Duramax manifold ever.
- Exceptional constant flow velocity
- Ports fit the largest CNC race heads
- Equal port to port pressure balance
- Computational Flow Dynamics, CFD, confirmed design
- Supplied with Banks/Cometic big port gaskets
- Outlet area matched T6 flange area
- Special proprietary high-temp/high-strength alloy