I was told on here that factory reverse lip valve covers would work. Tried real hard to make them work and was never happy. Did some research on my own and out that cometic gaskets makes a valve cover gasket just for the w9s, and it fits perfectly. Then discovered that All Pro makes a valve cover just for w9s. Have recently learned that Doug Lee now makes a w9 specific valve cover also. You can also call Moroso fab shop and they will also make you the correct valve covers. Can you get by with factory pattern valve covers, sure but they don't fit out of the box. Why would you if the correct ones are available.