Our Products #4742509

Direct Mercruiser replacement for your 496 Mag or 496 HO engine.No additional custom tails to buy. You dont need to remove your stock exhaust hose to install our kit, a true plug and play system.This new kit introduces CMIs new low cost satin finish. For an additional charge you can have our classic high polished stainless finish.1 78" id primary to get peak horse power and torque.Mandrel bent and formed from High quality 316L grade material.Fully post annealed to reduce stresses built up in the header during the manufacturing processThe only seamless water jacketed header manufactured. No welded inner primaries or water jacketed tubes to crack and leak.More water jacketed protection than your stock exhaust.Approved by Mercruiser to not void warranty on the motor, with the exception of water reversion.Same high quality semi automated welding as used on all racing applicationsPatented Cool Collar design provides a short hot section at the flange, which helps minimize the possibility of water ingestion in to the engine.This kit is price competitive to other aluminumstainless manifold systems with superior performance and extended life span in harsh marine environments.No cast parts to crack, all CMI collectors are forged from American made stainless steel.

CMI Big Tube headers enable big block engines with 540 cubic-inch displacements or more to deliver peak horsepower and torque throughout the entire operating range. CMI Big Tube Headers are proven to withstand one of the toughest marine environments on earth offshore racing and have powered more National and World Championship boats than all other brands combined. CMI Big Tubes can be custom stepped in any configuration to meet any engine builders requirements.The fully polished CMI Big Tube systems are offered with the largest inside diameter options available on the market, including 2 18-, 2 -, and 2 38-inch inside diameters for any step combination. CMI offers a range of exhaust tailpipe options, as well as CMI's Sound Choice selectable silencing system, to complete any installation. All CMI Big Tube systems include stainless steel cooling fluid distribution tubes, header attaching bolts, all necessary gaskets and cooling fittings required for installation. Tailpipes sold separately.

CMI's new Small Block Headers are a cut above the rest. These performance headers increase horsepower 10+ and improve fuel consumption. Small Block headers boost mid-range torque by a whopping 15%, giving you an advantage over other boaters.This system incorporates CMI's patented "Cool Collar" design that keeps headers cool to the touch and "Flex Flare" connections for easy installation. Headers are constructed of 316L stainless steel for the utmost durability and are available fully polished or with a satin finish.Package comes complete with all required mounting hardware. Headers include a one year limited warranty.

CMIs Big Elbow Top Race Systems are precision-built for Sportsman-class racers who expect the most from their 510 cubic-inch carbureted engine or 600 cubic-inch engine equipped with a blower package. This race-style header system has a superior track record when it comes to getting to the finish line. Racers participating in APBA, SBI, OSS and USO competitions have found CMI Big Elbow Top Race headers help produce more torque and raw horsepower than any competitive exhaust products. CMI Big Elbow Top headers feature a 15 -inch long primary runner exhaust tubes and a 4 -inch inside diameter collector designed for 4 -inch inside diameter tailpipes. CMI also offers a custom-designed stepped system for high-horsepower applications that require larger diameter exhausts, which can be built to meet specific installation parameters. Tailpipes are sold separately.Best pricing and availability through one of our CMI Distributors or CMI Authorized Dealers.click here for details.

The CMI 496 Sport Tube Performance Package delivers improved performance across the entire operating range of any 496 engine package. When applied to a stock 496 engine, this package will help to increase horsepower, boost mid-range torque, improve fuel economy across the power curve and enhance the engine's overall running quality. The package comes complete with all required mounting hardware plus CMI's exclusive 496 Relocation Kit, which includes all brackets, hoses and hardware needed to make relocation of select engine components easier.A 496 Sport Tube Performance Package is also available for most sport boats equipped with a 496 engine package and CORSA* Performance Y-pipe diverter system.

CMI Diverter Y-Pipes conveniently allow the operator to switch from straight exhaust pipes to the original thru-prop exhaust system when quieter operation is required. CMI Y-pipes with coned ends make hose assembly easy on all 496 engine applications equipped with factory riser systems, transom tips, Mercruiser Bravo-style drives and a bullhorn. The Y-pipe design also allows users to add a free breathing exhaust tip to the assembly. CMI recommends installation of baffled tips for most

CMI Sound Elimination Systems mufflers offer proven sound reduction technology that enables boaters to operate their performance boats in areas where sound emissions are restricted. This system should reduce sound emissions to levels as low as 85 decibels (dB) in many applications, which is below most sound emission regulations. The mufflers are engineered to reduce sound without restricting the exhaust or creating unwanted backpressure, which can inhibit the engine from reaching peak performance power. Mufflers can be installed on any exhaust system with tailpipes ranging from four to six-inches in diameter, which covers the full range of inboard or stern drive-powered recreational and performance boat applications up to 1200 horsepower. CMI Sound Elimination Systems mufflers are made from 304 series stainless steel, and have fewer moving parts than competitive models to ensure long-lasting durability and reliability for nearly any application.Clamp-on options include a 4 model to fit tip-style tailpipes ; a 4.5 inch model to fit thru-transom tailpipes; and a 5-inch model for larger tailpipe diameters primarily used with CMI Big Tube Racine Header Systems.

CMI External Sound Choice silencers allow the operator to muffle high decibel sound waves emitted through the exhaust with simply a flip of a switch. External Sound Choice stainless steel silencers feature a fully-polished, mirror-like finish and can be installed on most gas or diesel engine applications. Heavy duty shaft and butterfly valves are standard to meet requirements of high-horsepower propulsion systems. CMI Sound Choice System are pneumatically operated, eliminating the risk of electrical spark hazards.