Custom Marine Inc. - Big Block Chevy

CMI 454/502 Direct Mercruiser Replacement E-Top Exhaust System, Satin

The CMI 454/502 E-Top Header Kit is a a true plug and play system. There is no need to purchase additional custom pipes. These are a direct replacement for your stock 454/502 engine. CMI headers offer more water jacketed protection than your stock exhaust can provide. CMI uses the same high quality semi-automated process on these headers as with the entire product line. These headers are fully post annealed to reduce stresses built up in the header during the manufacturing process. Best of all, 454/502 E-Top headers are made to last, they are mandrel bent and formed from hight quality 316L grade material. There are no parts to crack, all CMI collectors are forged from American made Stainless Steel.

Note: All CMI Systems are sold without Talipipes

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 3-4 WEEKS

CMI 454/502 Direct Mercruiser Replacement E-Top Exhaust System, Polished

The CMI 454/502 E-Top Header Kit is a a true plug and play system. There is no need to purchase additional custom pipes. These are a direct replacement for your stock 454/502 engine. CMI headers offer more water jacketed protection than your stock exhaust can provide. CMI uses the same high quality semi-automated process on these headers as with the entire product line. These headers are fully post annealed to reduce stresses built up in the header during the manufacturing process. Best of all, 454/502 E-Top headers are made to last, they are mandrel bent and formed from hight quality 316L grade material. There are no parts to crack, all CMI collectors are forged from American made Stainless Steel.

Note: All CMI Systems are sold without Talipipes

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 3-4 WEEKS

CMI 520 E-Top Satin Exhaust Header System

• Increases in Horsepower up to 31 HP
• Direct replacement – works with existing exhaust outlets
• Improved mid-range acceleration and torque
• Polished and satin finish available
• Patented “Cool Collar” design
• Mandrel bent and formed from high quality 316L grade stainless steel

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 3-4 WEEKS

CMI 520 E-Top Polished Exhaust Header System

• Increases in Horsepower up to 31 HP
• Direct replacement – works with existing exhaust outlets
• Improved mid-range acceleration and torque
• Polished and satin finish available
• Patented “Cool Collar” design
• Mandrel bent and formed from high quality 316L grade stainless steel

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 3-4 WEEKS

CMI Merc 500 EFI Replacement E-Top Exhaust System

CMI Elbow Top headers are designed for direct replacement of most stock cast manifolds. Top engine builders and stern drive manufacturers who want to optimize performance of small- or big-block marinized engines prefer CMI Elbow Top headers for their engines. CMI E-Top systems offer separated exhaust passages with long individual exhaust tube runners to minimize cylinder to cylinder influence and improve exhaust gas scavenging, which allows the engine to breathe freely and deliver peak performance power. All CMI Elbow Top Systems include water distribution tubes, cooling water bypass couplings installed on the collector elbow, by-pass hose fittings, attaching cap screws, exhaust port gaskets, hose clamps and cooling water inlet fittings needed for most installations.

Note: All CMI Systems are sold without Tailpipes 

IN STOCK

CMI Fusion Integrated Tailpipe Big Block Chevy Exhaust System

This is the all new, salt water rated "Fusion" Performance Header system from CMI. For years Custom Marine has produced custom exhaust systems for just about every Hi-Performance application.  But now CMI has set their sights on offering an affordable Performance Header system for the entry level Hi-Performance market with the new "Fusion" header system. This new header was designed as an affordable upgrade to exhaust manifold systems for engines needing to support upwards of 600 horsepower, while using standard Mercury Bravo exhaust exit locations. These headers are offered in the "Platinum" series finish which features a brushed satin lower section,  then mating it to a highly polished top tailpipe to produce a striking appearance on any engine. By integrating the tailpipe CMI can reduce costs to the user and eliminate costly clamps and gaskets. Premium 316L stainless steel construction, as well as the patented cool collar exhaust flange make for a durable header that will offer years of trouble free service. While the standard version is designed to fit stock Mercruiser Bravo exhaust exit locations, there are also two custom fit tailpipe options available that will allow the header to be assembled at the factory to your boats specifications. Up to a 2" vertical and/or horizontal correction can be made from the stock locations which allows this header to fit a huge range of options. (Additional charges apply)

Note: This system does not have separate tailpipes. It's pipes are set up for standard Bravo hole locations.

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 3-4 WEEKS

CMI's Gen-X Headers are a direct factory replacement for Mercury Racing HP525EFI, HP600SCi and HP700SCi engines.

These are sold as a "pair of headers"

The new design increases water fill keeping the headers full at all time, creating cooler temperatures, which leads to improved longevity and a little extra horsepower.

Featuring more equalized primaries for improved performance, the straight-back headers with downturn collectors work with existing tailpipes and are easy to install. Constructed of quality 316L domestic stainless steel makes for one tough header with a sleek stylish look.

IN STOCK.

• Increases in Horsepower up to 48 HP
• Downturn collector improves water fill
• Improved mid-range acceleration and torque
• Polished finish available
• Equalized primaries for greater performance
• Patented “Cool Collar” design
• Mandrel bent and formed from high quality 316L grade stainless steel

Note: All CMI Systems are sold without Tailpipes

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 3-4 WEEKS

CMI Big Block Chevy E-Top Platinum Exhaust System

CMI Elbow Top headers are designed for direct replacement of most stock cast manifolds. Top engine builders and stern drive manufacturers who want to optimize performance of small- or big-block marinized engines prefer CMI Elbow Top headers for their engines. CMI E-Top systems offer separated exhaust passages with long individual exhaust tube runners to minimize cylinder to cylinder influence and improve exhaust gas scavenging, which allows the engine to breathe freely and deliver peak performance power. Each header features a permanently attached, non-adjustable exhaust tailpipe configured to meet precise specifications for stan¬dard transom layouts and placement of thru-hull exhaust tips. All CMI Elbow Top Systems include rubber water distribution tubes, cooling water bypass couplings installed on the collector elbow, by-pass hose fittings, attaching cap screws, exhaust port gaskets, hose clamps and cooling water inlet fittings needed for most installations.

Note: All CMI Systems are sold without Tailpipes

The picture for this item is shown with a Stainless distribution tree, but this part includes a rubber distribution tree.

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 3-4 WEEKS

CMI Big Block Chevy E-Top Platinum Exhaust System

CMI Elbow Top headers are designed for direct replacement of most stock cast manifolds. Top engine builders and stern drive manufacturers who want to optimize performance of small- or big-block marinized engines prefer CMI Elbow Top headers for their engines. CMI E-Top systems offer separated exhaust passages with long individual exhaust tube runners to minimize cylinder to cylinder influence and improve exhaust gas scavenging, which allows the engine to breathe freely and deliver peak performance power. Each header features a permanently attached, non-adjustable exhaust tailpipe configured to meet precise specifications for stan¬dard transom layouts and placement of thru-hull exhaust tips. All CMI Elbow Top Systems include rubber water distribution tubes, cooling water bypass couplings installed on the collector elbow, by-pass hose fittings, attaching cap screws, exhaust port gaskets, hose clamps and cooling water inlet fittings needed for most installations.

This Kit includes an upgrade to a Stainless Steel Water Distribution Tree.

Note: All CMI Systems are sold without Tailpipes

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 3-4 WEEKS

CMI Big Block Chevy E-Top Polished Exhaust System

CMI Elbow Top headers are designed for direct replacement of most stock cast manifolds. Top engine builders and stern drive manufacturers who want to optimize performance of small- or big-block marinized engines prefer CMI Elbow Top headers for their engines. CMI E-Top systems offer separated exhaust passages with long individual exhaust tube runners to minimize cylinder to cylinder influence and improve exhaust gas scavenging, which allows the engine to breathe freely and deliver peak performance power. Each header features a permanently attached, non-adjustable exhaust tailpipe configured to meet precise specifications for stan¬dard transom layouts and placement of thru-hull exhaust tips. All CMI Elbow Top Systems include rubber water distribution tubes, cooling water bypass couplings installed on the collector elbow, by-pass hose fittings, attaching cap screws, exhaust port gaskets, hose clamps and cooling water inlet fittings needed for most installations.

Note: All CMI Systems are sold without Tailpipes

The picture for this item is shown with a Stainless distribution tree, but this part includes a rubber distribution tree.

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 3-4 WEEKS

CMI Big Block Chevy E-Top Polished Exhaust System

CMI Elbow Top headers are designed for direct replacement of most stock cast manifolds. Top engine builders and stern drive manufacturers who want to optimize performance of small- or big-block marinized engines prefer CMI Elbow Top headers for their engines. CMI E-Top systems offer separated exhaust passages with long individual exhaust tube runners to minimize cylinder to cylinder influence and improve exhaust gas scavenging, which allows the engine to breathe freely and deliver peak performance power. Each header features a permanently attached, non-adjustable exhaust tailpipe configured to meet precise specifications for stan¬dard transom layouts and placement of thru-hull exhaust tips. All CMI Elbow Top Systems include rubber water distribution tubes, cooling water bypass couplings installed on the collector elbow, by-pass hose fittings, attaching cap screws, exhaust port gaskets, hose clamps and cooling water inlet fittings needed for most installations.

This Kit includes an upgrade to a Stainless Steel Water Distribution Tree.

Note: All CMI Systems are sold without Tailpipes

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 3-4 WEEKS

CMI Big Block Chevy Sport Tube Exhaust System, 6" Taller, Polished

CMI Sport Tubes are a superior long tube header designed for both racing or virtually any high-performance application. For big- and small-block applications where maximum scavenging and horsepower are required, CMI Sport Tube headers deliver peak performance and power from naturally aspirated engines that generate more than one horsepower per cubic inch of displacement.

The all polished Sport Tube system is offered with a range of exhaust tailpipe options, as well as CMI's Sound Choice™ selectable silencing system. Each system includes all header attaching bolts, gaskets and cooling fittings required for installation.

Note: All CMI Systems are sold without Tailpipes

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 3-4 WEEKS

CMI Big Block Chevy Sport Tube Exhaust System, 9" Taller, Polished

CMI Sport Tubes are a superior long tube header designed for both racing or virtually any high-performance application. For big- and small-block applications where maximum scavenging and horsepower are required, CMI Sport Tube headers deliver peak performance and power from naturally aspirated engines that generate more than one horsepower per cubic inch of displacement.

The all polished Sport Tube system is offered with a range of exhaust tailpipe options, as well as CMI's Sound Choice™ selectable silencing system. Each system includes all header attaching bolts, gaskets and cooling fittings required for installation.

Note: All CMI Systems are sold without Tailpipes

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 3-4 WEEKS

CMI Big Block Chevy Standard Bravo Sport Tube Exhaust System, Polished

CMI Sport Tubes are a superior long tube header designed for both racing or virtually any high-performance application. For big- and small-block applications where maximum scavenging and horsepower are required, CMI Sport Tube headers deliver peak performance and power from naturally aspirated engines that generate more than one horsepower per cubic inch of displacement.

The all polished Sport Tube system is offered with a range of exhaust tailpipe options, as well as CMI's Sound Choice™ selectable silencing system. Each system includes all header attaching bolts, gaskets and cooling fittings required for installation.

Note: All CMI Systems are sold without Tailpipes

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 3-4 WEEKS

Stock Replacement wet tailpipes for use with Mercruiser 525 Headers, CMI Gen-X or Hardin Hurricane Lite Headers. Replaces OEM Mercury Part Number 8M0025008.

Stock Replacement wet tailpipes for use with Mercruiser 600 / 662 / 700 Headers.

Replacement HP 500 CMI Tail Pipes Standard Bravo, Early Model

These are factory replacements HP 500 EFI Tail Pipe replacements for Mercury Flange Header Early Models that have a straight jump hose.

Mercury OEM Part Numbers: 848739A1, 848735A1

Replacement HP 500 EFI Mercury Late Model Tail Pipes with 180° Jump Hose

For Stock Bravo Hole Location

Mercury OEM Numbers: 8M0053624, 845236A1