Small Block 6" Stainless steel "SA" riser pipes are designed to replace stock Mercruiser Bravo exhaust with 6" riser block between manifold & Riser. 3/4"npt fitting is used on front of pipe for thermostat housing that have (4) 1" hoses water to go to exhaust manifolds if needed click on (ADD BUNG). Shift bracket, ECM, or EFI brackets available as bolt on or welded to the risers.To order see PowerFlow Accessories or Related Products. They can also be used with our Aluminum "S" pipes part number 02-1225 for under swim step applications.