Exhaust Headers for Nissan XTerra Pathfinder Frontier (2005-2008) 4.0L EnginePerformance Exhaust Headers for 2005 2008 Nissan Frontier, Pathfinder, Xterra (VQ40DE D40, R51, N50) What it Does: Replaces the restrictive, crack prone factory cast iron manifolds with high flow stainless steel headers to optimize exhaust scavenging and reduce backpressure. The Stock Frontier, Pathfinder, Xterra Exhaust Restriction The OEM cast iron manifolds on the 4. 0L VQ40DE engine are a documented failure point. Due to the density of the cast