Custom Marine headers are made from high-quality 316L and 317L stainless steel tubes and heat treated (annealed) for added stress relief and superior durability. All CMI headers are hand-welded and polished by skilled artisans who are proud of the top-quality exhaust systems they build. Every CMI exhaust system is designed to deliver the highest level of quality and peak on-water performance every CMI customer demands.
Below are some of our most popular header styles. Beyond E-Tops, Sport Tubes and Big Tubes, CMI also offers custom headers for Ford, Chrysler and any other platform. All headers are offered in either a polished or satin (brushed stainless) finish and are post annealed. Most common are 316L inner and outer tubes, but we also offer headers in Duplex stainless, Inconel and titanium.
Custom Marine has headers for your small single engine set, up to the wildest quad engine layout. If you can dream it, we can build it. From one off prototypes to high-volume runs, Custom Marine has a solution for every application.
Although CMI is known for water jacketed “eye candy,” we also have vast experience in the off-road market. If you are busing a Sand Car or a Trophy truck, CMI can help. Your options are endless at Custom Marine. Let’s get started today!
Separate exhaust passages with long individual exhaust tube runners minimize cylinder-to-cylinder influence and improve exhaust gas scavenging
Long tube headers that deliver peak performance and power from any naturally aspirated engine
Replacements for taller, leaned in or leaned out 525EFI – 700sci Mercury racing engines
2 1/8-, 2 ¼-, and 2 3/8-inch inside diameters for all big power applications, either naturally aspirated or supercharged