PPE does have a intak manifold
I assume he is talking about this one
2004.5 - 2005 LLY Intake Manifold [LLYIntakeManifold] - $428.95 : Pacific Performance Engineering, Diesel Performance Technolgies
I just have mine blocked..dont have any info on the manifold
but as for being blocked, i really did not notice any change at all - just peace of mind that's all