The most restrictive part of your 2004-2005 VIN '2' LLY Duramax intake is the factory plastic air horn. It connects directly to the factory turbocharger inlet and is proof that not all engineers are 'A' students. It's not uncommon to see 3-4 PSI of pressure drop across the factory piece. This pressure drop translates to about 10 psi of boost pressure at high load.Before you buy exhaust, before you buy an intake, buy this upgrade. Works with factory LLY style intake and aftermarket LLY style intakes.
Does not mate to LBZ intake piping.
Includes: LLY High Flow Inlet air horn