The GM 12637647 Updated Driver Side Exhaust Manifold for your 2001-2010 GM 6.6L Duramax features a “full bore” unlike the factory exhaust manifold that is “kinked or dented” for additional clearance. The increased flow will “balance” the engine and provide increased spool-up, throttle response and better overall performance. This GM OE part is constructed to the same high quality standards as your factory exhaust manifold.
