Katech designed and manufactured a cast aluminum valve cover for the LS1 and LS6 engines. These covers are a raised design which allows clearance for any LS1 style rocker arm. Unlike the C5-R covers, these use the stock gasket for sealing. This eliminates the expensive cylinder head o-ringing process. Just like the stock covers, these are totally isolated from the head by rubber. That means they will seal just as good as the stock covers do.