Holley Sniper 2 EFI Self-Tuning Fuel Injection System 550-511-3XK
The best-selling EFI conversion in the world – now in an even more advanced and user-friendly version.
Holley Sniper 2 EFI is developed for those who want to convert from carburetor to modern electronic fuel injection – without making the installation complicated. The system fits directly onto 4-barrel intake manifolds with a 4150 flange and combines ECU, injectors, sensors and control in one compact throttle body unit.
Sniper 2 builds upon the experience from the original Sniper EFI, but has been upgraded with a completely new generation ECU, improved noise immunity, optimized throttle design, improved connectors and even more stable self-calibration. The result is a solution that operates reliably – even in older vehicles with fluctuating wiring quality and classic alternators.
The system provides:
Easy and reliable cold starts
Stable idle
Smooth acceleration
Improved fuel economy
More precise fuel control
Possibility of timing control (with Hyperspark integration)
Sniper 2 can handle up to approx. 650 HP naturally aspirated or 575 HP with boost, thanks to four integrated 100 lb/hr injectors.
Installation can be carried out at home in the garage. The system requires only four basic connections: Battery +, Battery –, Switched 12V and RPM signal. The built-in Setup Wizard then guides you through a simple startup, where you only answer a few questions about engine size, camshaft type and idle – and the system begins self-calibration automatically. No laptop is required.
What is included in the Master Kit (550-511-3XK)
This is the complete version with fuel system included.
Included components in the Master Kit (550-511-3XK)
• 4-barrel EFI throttle body (4150 square bore flange)
• Integrated ECU (engine control built into throttle body)
• 4 pcs. 100 lb/hr high-flow injectors
• 3.5" color touchscreen display for setup and tuning
• Complete plug-and-play wiring harness
• Wideband Bosch LSU 4.9 O2 sensor incl. weld bung and installation kit
• MAP sensor
• TPS sensor (contactless magnetic type)
• IAT sensor
• IAC valve
• External inline high-pressure fuel pump
• Fuel pressure regulator
• 20 ft. 3/8" Vapor Guard fuel hose (feed and return)
• Fuel filters
• Bulkhead fitting for tank return
• Installation hardware and gaskets
New features in Sniper 2
Improved ECU with high resistance to RF noise and interference
Redesigned throttle shaft and throttle plates for more linear throttle feel
Integrated kickdown function for e.g. GM TH350/400, 200-4R/700R4 and Ford C4/C6
Improved injector connectors for higher reliability
Expanded input/output options (ground inputs/outputs, TPS 0-5V output, tach output)
Serial-numbered throttle body for improved warranty and service handling
Sniper Ecosystem – expansion options
Sniper 2 is part of Holley’s complete EFI ecosystem and can be combined with:
Hyperspark ignition system (coil, box and distributor)
Power Distribution Module (PDM) for centralized power management
5" Digital Dash
Bluetooth module for iOS and Android
CD box and MSD adapters
With the PDM module, the entire EFI and ignition power management can be gathered in one place, where only battery and switched 12V are supplied. This significantly reduces installation time and minimizes the risk of errors.
Who is the system ideal for?
Classic V8 builds
Restomod projects
Street performance vehicles
Mild boost setups
Projects where modern drivability is desired without a full standalone ECU
Installation guide
