Equipped with our performance Stainless Steel High Flow Risers, these are our best performing systems. They are a direct replacement for stock Mercruiser manifolds in Bravo and Alpha applications that utilize a 3" spacer block between the manifolds and risers and where the exhaust outlets exit through the transom in the stock 3" taller location. The 16” long riser is a must with High Performance camshafts to prevent reversion (water ingestion). Becuase of their added lenght, these will NOT work with Selector systems or stock “S” pipe connections. (there is an additional charge on some late model EFI systems). Complete systems come with all necessary bolts, gaskets and fittings. Standard with black Fusioncoated finish- optional finishes are available. Specify the correct accessory brackets and options when ordering. Brackets extra.