Exhaust Manifold Headers for Chevy Impala & Monte Carlo SS (2004-2005) 3.8L Supercharged EngineUnlock Your L67's Potential: Stainless Steel Headers for GM 3. 8L Supercharged V6 Eliminate backpressure and let your supercharger scream. The GM 3800 Series II Supercharged engine (L67) is legendary for its torque and reliability, but the restrictive stock cast iron manifolds hold it back. Our T 304 Stainless Steel Header Kit replaces those heavy, flow choking manifolds with a high performance 6 2 1 design. By improving exhaust scavenging, you reduce