The LS6 engine valley cover is an excellent upgrade over the factory LS1 PCV system. This cover eliminates the two rear valve cover PCV hose connections as well as the PCV hose and PCV valve itself. The built-in baffle improves crankcase ventilation and decreases the quantity of oil and contaminants that make it into your intake. The built-in, no-maintenance restrictor eliminates the need for a PCV valve.
Direct bolt-on for 2001-2003 LS1 engines. Earlier LS1 engines require some minor cutting of a boss in the engine valley that interferes with the cover baffle. For vehicles with the LS6 engine valley cover (part #12568002) this is also an upgrade because it eliminates the OEM PCV valve assembly. Also required for the conversion is a valve cover plug (part #12568011), a 5/16" vacuum cap and the valley cover PCV hose (part #12594779).
The complete swap kit includes everything you need to swap to this valley cover: the valley cover, PCV hose, and valve cover plug.
GM Part # 12577927 - LS6 engine valley cover
GM Part # 12558178 - LS6 engine valley cover gasket
GM Part # 12594779 - LS6 engine valley cover PCV Hose
GM Part # 12568011 - Valve cover plug for LS-Series Engine
2004-2005 Cadillac CTS-V
2004 Chevrolet Corvette
2004 Pontiac GTO
GM Gen III LS-series engines
A how to guide for the conversion is available here (please ignore the portion of the instructions regarding re-using the factory PCV valve - this 2004 valley cover has a built-in PCV restrictor and does not require a PCV valve).