SKU: 18286945036

HP EFI ECU & Harness Kits - 550-601

Sale price$1237.47 Regular price$1374.97
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Ships within 48 hours · Estimated delivery Jul 10 - Jul 15

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Description

HP EFI ECU & Harness Kits - 550-601Overview: Looking for a plug and play alternative for your stock or built late model factory EFI engine? How about a replacement ECU for your older Holley C950? Holley has you covered. HP EFI ECU and harness kits are designed to be used with popular factory EFI engines as an alternative to the factory ECU and harness or as a replacement for your C950 ECU. The HP allows you to accurately control the fuel and ignition of your engine along with

Overview:

Looking for a plug and play alternative for your stock or built late model factory EFI engine? How about a replacement ECU for your older Holley C950? Holley has you covered. HP EFI ECU and harness kits are designed to be used with popular factory EFI engines as an alternative to the factory ECU and harness or as a replacement for your C950 ECU. The HP allows you to accurately control the fuel and ignition of your engine along with additional controls for nitrous, boost, or water meth.

Features:

  • NEW V2 SOFTWARE FEATURES
  • “Quick Start” ignition and fueling strategy for LS x Engines
  • Data Logger. Scalable axes, Smoothing, Multiple graph view ability, Pre-defined notes fields and many more
  • Strip Chart Real-Time Data Viewer
  • Integrated Boost Control - Boost vs Time, Boost vs Gear (Time or RPM), Boost vs RPM, Boost vs Speed, Launch control. Boost launch builder, Over-boost safeties, Boost scramble
  • Traction Control - Power reduction via timing, nitrous percentage or boost (Requires Davis Technologies Holley Module)
  • “Quick Start” fueling for all engines
  • Option for VE based fueling strategy
  • Fuel Map and Learn Function Smoothing
  • Configurable User Password Protection
  • Fully Configurable lap top Gauge Panel
  • FEATURES
  • Optional 5.7” full-color touchscreen LCD allows easy on-the-fly tuning,data-logging or can be used as an easy to see graphical gauge panel
  • Eight sequentially driven 8:2 peak and hold injector drivers, capable of driving up to 16 low or high impedance injectors as a standard feature. Multiple staged injector strategies
  • Eight channel Distributorless Ignition (DIS)outputs capable of directly driving “Smart” ignition coils or Holley DIS coils. Will drive 2 wire coils with the addition of PN 554-112 high current coil driver module
  • Plug and Play control of factory GM 24x and 58x LSx engines
  • Integrated single channel wide band oxygen sensor control. Works with NTK or Bosch sensors
  • Internal data-logging standard with a huge 2GB of memory
  • 4 Stage progressive nitrous control
  • Turbo boost control
  • Integrated water/methanol injection control
  • Self-tuning fuel table strategy greatly simplifies tuning process
  • Individual cylinder fuel and spark control allows you to unlock your engine’s potential
  • Works with 4, 6, 8 cylinder engines
  • Unique lb/hr based fueling strategy greatly simplifies and commonizes tuning
  • Advanced idle, closed loop, and enrichment strategies allow for very stable operation
  • ECU is fully potted and can be mounted in the engine compartment or interior
  • Sealed automotive and marine grade connectors
  • Allows for use of common OEM sensors as well as customer sensor calibration input
  • Ignition Plug and Play with GM 24x and 58x LSx engines, GM HEI, Ford TFI, magnetic and hall effect trigger, and other ignition systems. New Plug and Play applications in process. Custom settings can be configured to allow many other applications
  • 1-5 Bar MAP sensor capability
  • Two channel knock control sensor Inputs for both one or two wire knock sensors
  • Dedicated fuel and oil pressure inputs
  • Controls both stepper and PWM Idle Air Control (IAC) motors
  • Speed density, Alpha-N, or combination fueling strategies
  • 4 Programmable high or low Pulse Width Modulated (PWM) outputs and 4 fully configurable inputs can be configured for use
  • 4 Stage nitrous oxide control
  • Fully featured nitrous control eliminates the need for a separate nitrous controller device
  • Can be configured “Wet” or “Dry” with closed loop feedback
  • Progressive control based on time, RPM, or boost, requires part # 554-111
  • Lean or rich safety cutoff
  • Full timing retard/control configurability per stage based on RPM or time
  • Integrated Water/Methanol injection control
  • Uses Holley Water/Meth solenoids specially designed and calibrated for use with this EFI system to allow the user to enter Water/Meth flow as a percentage of fuel injector flow for Water/Meth tuning precision unmatched in the industry

Application:

Year Make Model Submodel Engine Size
Universal

Specs:

Brand Holley EFI
Emission Code 3
Ignition Type Coil - (No Timing Control)
Ignition Type GM HEI Small Cap
Ignition Type Holley Dual Sync Distributor
Injector Connector Jetronic / Minitimer (Bosch)
Product Type HP EFI Kit
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 18286945036

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Stephanie Allen
Chelsea, US
★★★★★ 4
Comfy!
Special Size: 27.5" Full Length with Pockets, Size: Large, Color: Black
Super comfy, not as much tummy control as I would like but perfect for house work, going to the gym or grocery shopping. Love that these have pockets!! Thin so not too hot and stretchy too.
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Reviewed in the United States on April 1, 2026
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Meredith
New York, US
★★★★★ 5
Great leggings!
Special Size: 27.5" Full Length with Pockets, Size: Medium, Color: Black
These are great leggings! They’re my third pair. They are comfortable, lightweight, and fit great. I wouldn’t say they are buttery soft as compared to other leggings that are listed the same texture, however they are soft and smooth. The pockets are a must and are positioned perfectly.
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Reviewed in the United States on January 9, 2026
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Bailey Forzani
Port Orchard, US
★★★★★ 5
So excited I found these!
Special Size: 27.5" Full Length, Size: Small, Color: Black, Special Size: 27.5" Full Length, Size: Small, Color: Black
Extremely impressed with these leggings! These athletic leggings are absolutely amazing! The material is incredibly soft and feels so comfortable against the skin. The quality is top-notch, with a durable yet flexible fabric that moves perfectly with your body. They are completely squat-proof, which makes them perfect for workouts, and they stay in place without sliding down, no matter how much you move. Some of my more expensive name brand leggings don’t check all the boxes; as these do! These leggings truly combine comfort, quality, and performance—highly recommended! Also- I am 5’3/5’4 and these hit right at my ankle
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Reviewed in the United States on July 22, 2025
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LeAnn Y.
Natrona Heights, US
★★★★★ 5
Really soft and comfortable for the price!
Special Size: 27.5" Full Length, Size: Small, Color: Ocean Blue, Special Size: 27.5" Full Length, Size: Small, Color: Ocean Blue
These are soooo soft and the quality is amazing! They feel like they would be way more expensive! I love the color and get lots of complements.
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Reviewed in the United States on January 22, 2026
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J.D.E
Battle Creek, US
★★★★★ 5
Fabulous!
Special Size: 19" Capri with Pockets, Size: X-Small, Color: Flamingo Pink
These are AMAZING! Just received my first two pairs ( black and flamingo pink) and I am back ordering more! They are so smooth and soft and feel great! They fit so well-not to restrictive but have strength enough in the Lycra to look amazing (not the thin, flimsy, cheap tights/leggings). I live in the Sunshine State so I can wear these to workout and run indoor or outdoor practically year round. I prefer this shorter length because they are cooler to wear in the 95° heat 100% humidity. So hoping they make these in the green color and the bright blue color that is available in the full length active leggings! These are my new favorite crop active leggings! Please, please, please make more colors! Amazon, these are fabulous quality and style and at this price point, I'd buy every color and pattern available (I just don't do flesh tones).
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Reviewed in the United States on July 8, 2025

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