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Gen-X Headers

New! Gen-X Headers

Direct factory replacements for Merc 525 to 700 engines

Welded on distribution tube. Works with existing tailpipes. Quality 316L Domestic Stainless Steel. More equalized primaries for improved performance. Improved water fill to help the header last longer in harsh environments.

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496 E-top Headers

496 E-top Headers

Direct Mercruiser replacement for your 496 Mag or 496 HO engine.

No additional custom tails to buy. You don’t need to remove your stock exhaust hose to install our kit, a true plug and play system.

This kit is Price competitive to other aluminum/stainless manifold systems with superior performance and extended life span in harsh marine environments.

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Other Header Applications


CMI Industrial is proud of its heritage as a designer and manufacturer of top-quality sound and noise attenuation systems that have set the benchmark for quality and innovation. CMI has enjoyed a decades-long leadership position by offering unparalleled products and services, and maintaining industry-leading customer satisfaction.

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About Custom Marine Inc

One fact says it all: Over the last six years, Custom Marine headers, tailpipes and exhaust systems have been on more National and World Championship boats than all other brands combined. The reason is simple: When it comes to quality, performance and striking good looks, no one can touch CMI. No one even comes close!

Vision is the Key

Starting in 1984, Custom Marine Inc. quickly caught the attention of the offshore-racing community by producing custom designed headers and tailpipes that offered superior performance and quality to meet their high-performance needs.

Drawing on more than 100 years of stainless-steel welding and fabrication experience garnered from Wisconsin's premier paper-making machinery industry, CMI's Two-Piece Elbow Top was the company's first commercially available header, which became an immediate success due to the superior craftsmanship and attention to detail. This innovative new header boosted horsepower, proved to be more durable under race conditions, and looked better longer than any competitive products on the market.

Best pricing and availability through one of our
CMI Distributors or CMI Authorized Dealers...click here for details.


Leading The World In Innovation

Over the years, CMI has expanded tremendously -- in size and scope, but also in sheer Research & Development creativity. With top marine engineers and the best stainless steel craftsmen and artisans in the United States working together under one 98,000 square-foot roof -- housing one of the most complete and technologically advanced tube bending, forming and welding facilities in the world -- Custom Marine has emerged as the industry's unquestioned innovation leader, delivering firsts including;

  • The patented cool-collar accumulator, which eliminates header hot spots, cracking and the potential for water ingestion.
  • The flex-flare header-to-tailpipe attachment, which makes header/tailpipe connections easier and more forgiving to production hull variances
  • The Big Tube/Step Tube, the ultimate race header on the circuit today
  • Stainless-steel blower intake manifolds and custom-built 180-degree headers to maximize big blocks' torque potential.

True to our founding vision, Custom Marine is committed to producing the best marine exhaust systems in the world.

Best pricing and availability through one of our
CMI Distributors or CMI Authorized Dealers...click here for details.

Why CMI?

Every CMI header is built to exacting standards that have made them the number one choice for offshore racers and performance-oriented boaters who demand on-water performance.

CMI headers are manufactured using state-of-the-art materials, like 316L and Duplex stainless steel, offering superior corrosion resistance and durability. A unique, patented bending process assures uniform wall thickness and eliminates any rippling and crazing of the tubing during production. Semi-automated tungsten inert gas welding, plus heat treating of the complete manifold following assembly, significantly reduces internal stresses that commonly cause fatigue, corrosion and premature failure in most high performance applications.

To complement its header systems, CMI also manufactures custom tailpipes, exhaust accessories and integral mufflers for virtually any single, dual, triple or quad engine configuration, including small block or big block applications, Chevrolet and Buick V-6s and Ford 460 and SVO's.

With CMI, boaters get a combination of performance and reliability unparalleled by any competitive products on the market.

Best pricing and availability through one of our
CMI Distributors or CMI Authorized Dealers...click here for details.

It's all about Performance