Holley Sniper EFI

Holley Sniper EFI Self-Tuning Kit - Shiny Finish

Sniper EFI 4 Barrel Fuel Injection Conversion - w/ Handheld Sniper EFI Monitor

Part # 550-510
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This part is legal for sale and use on Uncontrolled (Non-Emissions Controlled) Vehicles.

See Emissions Details
Holley just brought EFI within range with Sniper EFI! Introducing Sniper EFI! Sniper EFI is economically priced so you can have all the benefits of Fuel Injection and still have money to finish or upgrade the rest of your ride! Perfect for street rods, muscle cars, off-road trucks, or nearly any carbureted vehicle. A Sniper EFI system can put an end to cold start issues, hesitations, vapor lock, and flooding. We also offer a full line of Sniper Hyperspark distributors, Sniper ignition boxes, Sniper coils, and other ignition components for those looking to round out their ride with a complete Sniper EFI, Ignition, and Fuel system! Upgrade to Sniper EFI and get the tactical accuracy of EFI today!


  • Dual Pattern bolt on carburetor replacement, designed to fit 4150 Flange & Spread Bore manifolds - (Spread Bore Sealing Plate Part #9006 is recommended)
  • Throttle body mounted ECU – no extra boxes to mount
  • Supports up to 650hp with Four 100 Lb/Hr Injectors!
  • Only 4 Wiring Connections Required! (Battery +, Battery - , Switched Ignition & RPM)
  • Internal fuel pressure regulator eliminates the hassle of plumbing an external fuel pressure regulator (Preset to 58.5 PSI)
  • Integrated ignition timing control & coil driver
  • High Resolution Full Color Touchscreen for Initial Setup, Tuning, and Gauge Displays.
  • Simple Calibration Wizard (Answer a few questions about your engine and it creates the base map, then starts tuning on its own!) - NO laptop required!
  • Self-tuning ECU means you don't have to be a computer/tuning wiz to have EFI!
  • Available in base & master kits (Master kits include complete fuel system consisting of; 20ft of 3/8" Vapor Guard Fuel Hose, 12-920 Fuel Pump, Filters, necessary hardware and bulkhead fitting to return fuel into the tank!)
  • The included Genuine Bosch LSU 4.9 Wideband Oxygen Sensor provides realtime Fuel Map Learn!
  • OEM Style TPS/IAC and Fuel Pressure regulator, for years of dependable service.
  • Included clamp-on oxygen sensor kit ensures a leak free oxygen sensor installation, with Stainless Steel T-Bolt clamps and a Stainless Steel (Weldable) oxygen sensor flange
  • Certified to ISO 8846, SAE J1171 & United States Coast Guard Requirements for Ignition Protection & Fire Resistance. Making Sniper EFI the perfect choice for carburetor to marine fuel injection conversions!
  • A Flame Arrestor is REQUIRED for marine installations, such as part number, 720-1 or 720-13
  • Patent Pending
United States Coast Guard Approved
Certified to ISO 8846, SAE J1171 Requirements
Brand Holley Sniper EFI
Coast Guard ApprovedYes
Emission Code3
Flange StyleDual Bolt Pattern
Fuel Pressure58.5 PSI
Injector Size100 lb/hr @ 58.5 PSI
Inlet / Outlet Size9/16-18 Female O-Ring (AN 6)
MAP Sensor2Bar
Max Horsepower Rating650 Naturally Aspirated
Model4150 EFI Conversion Throttle Body
Product TypeSniper EFI
Part Number550-510

This part is legal for sale and use on Uncontrolled (Non-Emissions Controlled) Vehicles.

The following vehicles are considered Uncontrolled (Non-Emissions Controlled) Vehicles:

  • 1965 and older U.S. manufactured California Certified vehicles
  • 1967 and older U.S. manufactured Federally Certified vehicles
  • 1967 and older Foreign manufactured vehicle

WARNING: It is against the law to install this part on an Emissions Controlled Vehicle

The following vehicles are considered Emissions Controlled Vehicles:

  • 1966 and newer U.S. manufactured California Certified vehicles
  • 1968 and newer U.S. manufactured Federally Certified vehicles
  • 1968 and newer Foreign manufactured vehicle
Quickstart Guide
Quickstart Guide for Part# 550-510
Instructions for Part# 550-510
Instructions for Part# 550-510
Holley EFI Dealers
Do you need a custom kit built for your application? Do you need a system installed and tuned? Click here to find the Holley EFI dealer in your area!
Sniper EFI SD Card Contents
Sniper EFI SD Card Contents

Have a question about this product?

  • Question

    I was wondering if the holley efi sniper would support a draw through blower like what I have. I have a magnacharger 122, (carb sits ontop), and I''m wondering if the sniper would suffice on my setup. Need to know if I can go with a sniper or if I would have to get a super sniper. The blower should run on single digit boost.

    By Derrick H. on October 16, 2019

    A standard Sniper EFI throttle body does not have the boost reference port provisions. The Super Sniper throttle body comes machined for the draw-through style boost reference port. The 550-518 Super Sniper is what we recommend for your application.
  • Question

    Wondering about the detail of the fuel graph the system uses. Is it 8x8, 16x16, smaller or larger? Is it adjustable via laptop such that I could set the high vacuum values to not as high and pickup clarity on my motor that makes little vacuum? Can I use a laptop and do extensive tuning or is the handheld it?

    By Andrew P. on January 9, 2020

    Answer The software is free to download. Most of the fuel tables are 31x31. Yes, it is nearly infinitely software adjustable for various engine combinations. The initial setup is done with the handheld, if you need to fine-tuning adjustments, the software is normally the best solution.
  • Question

    Can I run the Holley regulator/filter P/N 12-876 with this sniper system? I see this sniper system has a built-in regulator and wasn't sure if having a second one in-line will cause an issue.

    By Darin A. on November 25, 2019

    If you plan on running an external regulator, it is recommended to remove the regulator in the sniper EFI main body.
  • Question

    Will this work with a Ford AOD transmission? If so, what else do I need? Brackets? etc...

    By Sean S. on March 1, 2020

    This product does not have a C4 kickdown, Lokar has a cable kit for this application. The Sniper Stealth 4150 has the C4 kickdown however. Check out part number 550-870
  • Question

    What is the lowest I could set engine idle RPM?

    By Kyle T. on November 15, 2019

    In theory, a sniper unit could function below 100rpm. The engine itself would be the determining factor for that.
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Some parts are not legal for use in California or other states with similar regulations.