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Deck & Dash Hardware - Custom Marine (CMI)

8.2MAG and 8.2HO Mercruiser NON-Catalyst Exhaust Header System
Starting From:
$3,595.95

This Part has options, please click the button below to order.

8.2MAG and 8.2HO Mercruiser NON-Catalyst Exhaust Header System

650-8200 + Option(s)

This new Custom Marine header system was designed as a replacement to the 8.2HO and 8.2MAG ECT catalyst Mercruiser engines with the 2” tall riser on the cast manifold (Which is the most common Mercruiser uses). These risers are easily identifiable by the serial #M82018002 stamped into the riser flange.

The header system is slightly taller than the restrictive factory system due to the improved collector design and down slope. This new header system features a pre-catalyst sensor port provision and NO post cat sensor provision as this header is designed for use with the Cat-Eliminator test system. The headers will connect directly to the factory wet exhaust exhaust hose connection. The header system is available in Satin or Production polished versions.

Note: These headers are not legal for any purpose other than testing purposes and not for use on any state or federal waterway. A PHOTO of your setup must be sent in order to make certain that the correct headers and brackets are built and shipped as there as several versions of this engine package.

Big Tube FF Gasket
Your Price:
$17.99

Big Tube FF Gasket

650-34280

Big Tube FF Gasket (Sold Each)

4-5/8" ID
5-13/16" OD


Big Tube Rope Seal Clamp Assembly Kit
Your Price:
$99.99

Big Tube Rope Seal Clamp Assembly Kit

650-36240

Big Tube Rope Seal Clamp Assembly Kit

Parts Included:
  • (1) Jumper Hose 1.375" ID, 180 Degree
  • (2) Stainless Steel Hose Clamp #24
  • (1) Big Tube V-Band Clamp
  • (1) 1/4-20 x 3.5" Hex Screw
  • (1) Rope Seal, High Temp
  • (1) Bridge Spacer, for 4.5" ID Tailpipe

Big Tube Standard Rope Seal
Your Price:
$19.99

Big Tube Standard Rope Seal

650-38120

Big Tube Standard Rope Seal

Rope Seal for CMI Big Tube Headers, sold each.

Big Tube/Big E-Top Clamp Kit
Your Price:
$89.99

Big Tube/Big E-Top Clamp & Gasket Kit

650-41025

Big Tube/Big E-Top Clamp & Gasket Kit

This kit includes:
  • (1) Jumper Hose 1.375" ID, 180 Degree
  • (2) Stainless Steel Hose Clamp #24
  • (1) Big Tube V-Band Clamp
  • (1) Big Tube Flex Flare Gasket
  • (1) Rope Seal, High Temp

CMI 496 E-Top Polished Exhaust Header Systems
Your Price:
$3,799.99

CMI 496 E-Top Polished Exhaust Header Systems

650-13175

CMI 496 E-Top Polished Exhaust Header Systems

How to measure riser height

Direct Mercruiser replacement for your 496 Mag or 496 HO engine. 8-1/2" Stock Riser Height. Polished. No additional custom tails to buy. You don’t need to remove your stock exhaust hose to install this kit, a true plug and play system.

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 this kit, a true plug and play system.

  • 1 7/8" 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 process
  • Seamless water jacketed header. 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 applications
  • Cool collar patented flange design to eliminate the risk of getting water in the motor by the head flange
  • This kit is price competitive to other aluminum/stainless 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.
  • Works on 34.5" drive centers
  • Brings a race look to your stock engine.
  • Sophisticated engineering leaves your stock oil lines in place and only requires relocating your oil filter with a supplied bracket.
  • Step by step, do it yourself instructions using Mercury supplied engine schematics.
  • Exhaust Water Temperature Bungs Installed as Standard Equipment.
ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 2-3 WEEKS

CMI 496 Sport Tube Exhaust System
Your Price:
$5,499.99

CMI 496 Sport Tube Exhaust System

650-13169

CMI 496 Sport Tube Exhaust System

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.

Note: All CMI Systems are sold without Tailpipes

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 2-3 WEEKS

CMI Big Block Chevy E-Top Platinum Exhaust System

Starting From:
$2,999.99

This Part has options, please click the button below to order.

CMI Big Block Chevy E-Top Platinum Exhaust System

650-13055 + Option(s)

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 2-3 WEEKS

CMI Big Block Chevy E-Top Platinum Exhaust System

Starting From:
$3,299.99

This Part has options, please click the button below to order.

CMI Big Block Chevy E-Top Platinum Exhaust System, Stainless Tree

650-13062 + Option(s)

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 2-3 WEEKS

CMI Fusion Integrated Tailpipe Big Block Chevy Exhaust System

Starting From:
$3,445.34

This Part has options, please click the button below to order.

CMI Fusion Integrated Tailpipe Big Block Chevy Exhaust System

650-1391 + Option(s)

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 2-3 WEEKS

CMI Gen-X Direct Replacement Headers for HP525, HP600 and HP700 Engines
Your Price:
$5,799.99

CMI Gen-X Replacement Headers for HP525, HP600 & HP700 Engines

650-13020

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.

DUE TO THE MANUFACTURERS MINIMUM ADVERTISED PRICE, WE CANNOT DISPLAY OUR ACTUAL RETAIL PRICE HERE. PLEASE CALL US OR USE COUPON CODE CMI GENX TO ORDER AT OUR REGULAR PRICE.

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 2-3 WEEKS

CMI Tailpipe Flange
Your Price:
$89.99

CMI Tailpipe Flange

650-29000

CMI Tailpipe Flange

  • Height: 5"
  • Inner Dia: 4"
  • Outer Dia: 4-15/16"

Basis for constructing custom CMI tailpipes.


Exhaust Header To Riser Gaskets - CMI Elbow Top Tailpipe Gasket
Your Price:
$8.99

Exhaust Header To Riser Gaskets - CMI Elbow Top Tailpipe Gasket

650-34190

Exhaust Header To Riser Gaskets - CMI Elbow Top Tailpipe Gasket (each)

5" O.D. and 4" I.D.

Here is just a sampling of the popular exhaust manifold gaskets that we offer.  Each gasket is designed to withstand the high temperatures of marine exhaust applications.  Gaskets are sold individually.


525 Standard Mercruiser Replacement Tailpipes
Your Price:
$1,399.99

Hurricane Lite / 525 Standard Mercruiser Replacement Tailpipes - 8M0025008

650-39358

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

LS Exhaust Gasket
Your Price:
$27.99

LS Exhaust Gasket

650-34005

LS Exhaust Gasket

Sold Each


Sport Tube/Sweeper FF Gasket
Your Price:
$18.95

Merc 525/600/700 Gen-X, Hurricane Lite Flex Flare Gasket

650-34350

Sport Tube/Sweeper Flex Flare Gasket fits Merc 525/600/700 Gen-X, Hurricane Lite.

Sold Each


Elbow Top Clamp Kit
Your Price:
$46.99

Mercury Tailpipe Clamp Kit

650-36190

Clamp Kit for Mercury Tailpipes

This kit includes:
  • (1) Jumper Hose 1.125" ID, 180 Degree. Mercury
  • (2) Stainless Steel Hose Clamp #16
  • (1) Mercury Tailpipe V-Band Clamp
  • (1) Gasket kit for Mercury Tailpipes

Molded Rubber Distribution Tube
Your Price:
$79.99

Molded Rubber Distribution Tube

650-30180

Molded Rubber Distribution Tube


Rope Seal Clamp Assembly Kit
Your Price:
$89.99

Rope Seal Clamp Assembly Kit

650-41160

Rope Seal Clamp Assembly Kit

Parts Included:
  • (1) Jumper Hose 1" x 6"
  • (2) Stainless Steel Hose Clamp #14
  • (1) V-Band Clamp for Standard Rope Seal
  • (1) 1/4-20 x 3.5" Hex Screw and Nut
  • (1) Rope Seal, High Temp
  • (1) Bridge Spacer, for 4" ID Tailpipe

Small Block Chevy E-Top Headers - Satin

Starting From:
$2,795.99

This Part has options, please click the button below to order.

Small Block Chevy E-Top Headers - Polished

650-13157 + Option(s)

Small Block Chevy E-Top Headers - Polished

Works as stock Mercury replacement or for most Stern Drives and Jet boats. 4" Hose connection. Made from 316L Stainless Steel. Bolts directly in the existing location of your stock manifold.

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 2-3 WEEKS