Running an Alien cowl on a legacy 2-stroke Mercury 3.0L V6 outboard normally requires the factory Mercury exhaust boot, OEM part number 848817. This part is now NLA (No Longer Available) from Mercury Marine, Quicksilver, and Mercury Racing, leaving many 300X / 3.0L EFI engines without a proper exhaust outlet. Owners often run these motors without the boot, which can cause cowling damage and idle issues over time.
 
To solve this, Buckshot Racing #77 uses and recommends a 300x-style exhaust boot, developed by Code Red Racing & Design, as a direct functional replacement for the discontinued 848817 on Alien cowl 3.0L applications.
 
Fitment – Compatible Mercury 3.0L Models
This 300x exhaust boot is intended for legacy 2-stroke Mercury 3.0L EFI V6 outboards using an Alien cowl and the adapter plate that originally accepted part 848817. Typical fitment includes 300X (3.0L EFI) Pro Max, 300 (3.0L EFI) ProMax, and 300 (3.0L EFI) SuperMagnum models. In general, if your 3.0L EFI midsection was designed for the 848817 boot, this replacement boot will match that installation.
 
Role of the Exhaust Boot on 3.0L Mercury / 300x Engines
On a 3.0L Mercury with an Alien cowl, the exhaust boot controls how hot exhaust gas exits the exhaust adapter plate and how it meets the cowling pan and skirt. With the 848817 boot missing, exhaust gas discharges into the lower cowl area, where heat can soften, melt, or warp the cowling—especially on engines that see extended high-load use. Disturbed flow at the adapter plate can also affect idle stability, making the engine less consistent at low RPM during docking, trolling, or loading.
 
Mercury 300x Exhaust Boot Design and Material
The 300x exhaust boot is a direct functional alternative to the OEM Mercury 848817, designed for durability and high-temperature operation. Instead of flexible rubber, it is 3D printed from a nylon–carbon hybrid filament that withstands the elevated exhaust temperatures of the 3.0L platform while maintaining shape through repeated heat cycles.
 
This is a rigid component. It clips into the exhaust adapter plate and engages the cowling skirt, creating a defined exhaust path between the adapter and the cowl and reducing direct heat exposure to surrounding plastic parts.
 
Practical Effects on the 3.0L Mercury Platform
On 3.0L Mercury and 300x Alien cowl engines, the exhaust boot improves thermal control and idle behavior. Routing exhaust through a controlled outlet instead of into the lower cowl lowers localized heat on the cowling pan and skirt, helping prevent softening, blistering, and deformation.
 
Restoring a sealed exhaust path at the adapter plate can also improve idle stability, particularly at low speeds where exhaust flow around the midsection is more sensitive. The rigid composite construction maintains fit over time, avoiding the shrinking and sagging often seen with aged rubber boots.
 
Kit Contents and Installation
The 300x exhaust boot kit includes one (1) main 3D-printed exhaust boot and one (1) matching 3D-printed skirt clip, covering a typical 3.0L Mercury Alien cowl installation with no extra brackets or special hardware.
 
Installation can usually be completed without removing the cowling pan. The boot is aligned with the opening in the exhaust adapter plate, pressed in until it clips fully into place, then secured to the cowling skirt with the supplied clip.
 
On engines with modified or imperfect adapter plates, some installers choose to apply a small amount of high-temperature silicone at the boot-to-plate interface to enhance sealing; this is optional and not required for standard fitment.
 
Manufacturing
The 300x exhaust boot is manufactured in the USA by Code Red Racing & Design using 3D printing with a nylon–carbon hybrid filament. For Buckshot Racing #77, it provides a clean, repeatable solution to the discontinued Mercury 848817 on 3.0L Mercury 300X, ProMax, and SuperMagnum Alien cowl builds, restoring correct exhaust routing and helping protect the cowling on the 3.0L / 300x platform.
 
For technical support, contact Mike Hill at +1-714-697-1716 or mike@buckshotracing77.com