SKU: 34360476229

HP EFI ECU & Harness Kits - 550-601N

Sale price$1349.97 Regular price$1499.97
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Ships within 48 hours · Estimated delivery Jul 11 - Jul 16

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Description

HP EFI ECU & Harness Kits - 550-601NOverview: 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: 34360476229

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Hillary K
Charlottesville, US
★★★★★ 5
Great sweater for winters in the Midwest
Color: Black, Size: X-Large
Love this sweater! I went back and got another color! The fit is true to size and very comfy. The button detail on the sleeves just adds a little pizazz. The weight of the sweater is perfect for winters in the Midwest.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 30, 2026
K
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KatieMae
Battle Creek, US
★★★★★ 5
Flattering fit
Color: Dark Green, Size: XX-Large
This sweater is thick and stretchy but holds a nice shape, and is flattering on the body. The sleeves are nice and long too, which I really appreciate, being a tall person... the button detail is a great addition. True to size. I haven't washed it yet, and I imagine, based on the kind of woolly knit it is, that this sweater will eventually pill... but for now I'm enjoying being cozy and stylish. The deep green color is almost black green. I LOVE IT.
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Reviewed in the United States on February 2, 2026
G
Verified Purchase
GypsySoul
Draper, US
★★★★★ 5
Love it
Color: Dark Green, Size: Small
I got the dark green. Love the sweater and it's warm. I do layer the sweater as well. It is as pictured. Size is perfect to me. I like sweaters to be longer and a bit wider in case it is freezing and I need to layer it. This sweater is perfect for layering. It comes closer to my backside, it is a little wide and not snug, and I like that the sleeves come over my wrists
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on February 7, 2026
J
Verified Purchase
JB
Port Orchard, US
★★★★★ 1
Still soft but looks terrible after 1 wash. Save your money
Color: White, Size: Small, Color: White, Size: Small
Update: sweater looked great when I received. After 1 wash it looks terrible. Looks like it’s been washed too many times, material fuzzy and piled. After wearing it once, it snagged and the knit pulled through. I would NOT recommend. I had such high hopes. Save your money. Very nice sweater, especially for the price! I love the details of the buttons on the sleeves. It is SO soft. It’s not super thick as I can see my skin through it when pressing my hand up against fabric. However, it’s not see through when wearing it. It’ll be perfect in cooler weather and perfect in the winter with a coat but won’t cause me to overheat when in a heated environment. I do feel like it runs big. I could have sized down a size. Although I’m not sure if it’ll shrink after a wash or two.
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Reviewed in the United States on September 22, 2025
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Verified Purchase
Lynn M
Lake Worth, US
★★★★★ 3
Disappointed.
Color: Blue, Size: Large, Color: Blue, Size: Large
This sweater is so comfortable and very soft. It fits well in a flattering, oversized way. But after one wash it is pilled everywhere which makes it look old and shabby. It’s at a price point where I feel compelled to return it.
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Reviewed in the United States on January 10, 2026

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