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.
Please note: The LS6 valley cover is NOT compatible with the LS1 intake manifold. However, LS1 engines produced after 2002 came with the LS6 intake manifold from the factory. This kit will work as a bolt-on kit for LS1 engines produced after 2002 ONLY. 1997-2002 LS1 engine's must swap to the LS6 intake manifold in order to use this valley cover.
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
LS6 valley cover is NOT compatible with the LS1 intake manifold
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).