Vibrant 14331D T304 Stainless D-Port Header Flange 3/8" for GM LT1 L98 LB9 SBC

Vehicle Fitment

• 1985-1991 Chevrolet Corvette C4 (L98 5.7L V8, TPI)
• 1985-1992 Chevrolet Camaro (LB9 5.0L V8, TPI)
• 1985-1992 Pontiac Firebird / Trans Am (LB9 5.0L V8, TPI)
• 1992-1996 Chevrolet Corvette C4 (LT1 5.7L V8)
• 1993-1997 Chevrolet Camaro Z28 (LT1 5.7L V8)
• 1993-1997 Pontiac Firebird Formula / Trans Am (LT1 5.7L V8)
• 1994-1996 Chevrolet Caprice / Impala SS (LT1 5.7L V8)
• 1994-1996 Buick Roadmaster (LT1 5.7L V8)
• 1994-1996 Cadillac Fleetwood (LT1 5.7L V8)

Fitment Notes

• Fits GM Gen I L98 and LB9 TPI Small Block and Gen II LT1 Small Block V8 engines only - does not fit Gen III LS or Gen V LT engines
• D-Port (oval port) design - matches factory D-shaped exhaust port profile on LT1/L98/LB9 cylinder heads
• Port sizing optimized for standard wall round tubing - not for Schedule 10 weld fittings
• Sold in pairs - includes 2 flanges per set (one per cylinder bank)
• Requires custom header tube fabrication - tubes and hardware not included

Features

• Precision laser cut from 3/8" thick T304 stainless steel for a flat, distortion-free sealing surface
• D-Port (oval) openings accurately match the factory exhaust port profile for maximum flow efficiency
• CNC machined port openings optimized for standard wall round exhaust tubing
• T304 stainless steel resists corrosion, oxidation, and sustained high-heat exhaust conditions
• Compatible with TIG and MIG welding for custom turbo manifold and header fabrication
• 3/8" thickness provides superior rigidity and resistance to warping under thermal cycling
• 1-year limited warranty backed by Vibrant Performance

Specifications

• Style: Exhaust Manifold / Header Flange
• Engine Compatibility: GM LT1 (Gen II 5.7L), L98 (5.7L TPI), LB9 (5.0L TPI) Small Block V8
• Port Style: D-Port (Oval)
• Thickness: 3/8 in. (0.375 in.)
• Material: T304 Stainless Steel
• Manufacture Method: Laser Cut, CNC Machined
• Port Sizing: Optimized for Standard Wall Round Tubing
• Finish: Natural / Brushed Stainless
• Quantity: Sold in Pairs (2 Flanges per Set)

Included Components

• 2x Vibrant 14331D T304 Stainless Steel D-Port Exhaust Manifold Flanges

Product Description

The Vibrant Performance 14331D is a pair of T304 stainless steel D-Port exhaust manifold flanges precision laser cut and CNC machined for GM LT1 (Gen II 5.7L), L98 (5.7L TPI), and LB9 (5.0L TPI) small block V8 engines. The D-Port oval opening accurately matches the factory exhaust port profile on these cylinder heads, ensuring maximum flow efficiency when fabricating custom headers or turbo manifolds. At 3/8" thick, these flanges resist warping and distortion under sustained high-heat and thermal cycling conditions inherent to performance exhaust applications.

Port openings are optimized for standard wall round exhaust tubing, making the 14331D a weld-ready starting point for custom naturally aspirated or forced induction header fabrication across a wide range of GM F-Body, B-Body, and Corvette C4 applications. Sold in pairs - one flange per cylinder bank - and compatible with both TIG and MIG welding processes.