Our Civic EP2 4-1 Tubular Race Exhaust Manifold replaces the restrictive standard cast iron manifold and improves exhaust gas flow thanks to its stainless steel, CAD-designed construction, resulting in much improved throttle response and dyno-proven power gains. Features: Constructed from T304 stainless steel 4-1 design 73mm Bore Collector 57mm Outlet Diameter TIG welded Improved throttle response and gas flow Compatible with: Honda Civic EP2 2000-2005 models.