Replace corroded risers or increase riser height and hose clearance for inboard installations Exhaust system components take a beating from prolonged exposure to salt and fresh water and being constantly heat cycled. As a result they corrode at a rapid rate. Replacement is not uncommon. If combatting back-flow or clearance issues on a new installation, an 8" extension can make a big difference. These Sierra spacers provide the extra height to prevent water from traveling back into the riser when throttling down and they can also provide added clearance for exhaust hose routing. Engineered to be compatible with GM based Crusader marine engines, these riser extensions feature machined mating surfaces that eliminate additional preparation to establish a proper seal. Each riser is leak tested prior to paint to ensure quality. Sierra uses special casting techniques to create risers with uniform wall thickness. Sierra engineers parts to meet or exceed manufacturer specifications and has earned the confidence of engine manufacturers and technicians. Boaters and technicians can be assured of the fit and function of every Sierra part.