Headers Manifold Shorty for Hummer H2 (2007-2009) 6.0L 6.2LHigh Flow Shorty Header Manifolds for 2007 2009 Hummer H2 (LQ4 L92 GMT900) What It Does: Replaces restrictive, heavy cast iron factory exhaust manifolds with mandrel bent T304 stainless steel shorty headers to reduce backpressure and improve exhaust scavenging for better throttle response. The Stock H2 Weakness The OEM cast iron manifolds found on the 6. 0L and 6. 2L GMT900 platform are prone to significant thermal stress, often leading to warped