The Edelbrock Exhaust Crossover Plugs are designed mainly for use in marine and off-road applications. They are made of cast aluminum and install into the exhaust crossover without any modifications. These plugs are available in non-EGR styles and use both electric and manual choke. The basic operating RPM ranges from idle to 5, 000. It also increases torque and horsepower at RPM ranges. These plugs are designed for use on emissions equipped vehicles. Gaskets are recommended.