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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:
- 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
4.0 ★★★★★
Based on 8 reviews
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Product Reviews
★★★★★ 5
Loooove these shoes!
Size: 7.5 Wide, Color: Chestnut Brown Faux Leather
I have these in several colors, and they’ve become a true staple in my wardrobe.
The Amazon Essentials Women's Belice Comfortable Slip-On Ballet Flats are exactly what I look for in an everyday shoe—simple, versatile, and comfortable right out of the box. The slip-on design makes them super convenient for busy days, and they pair effortlessly with everything from jeans to dresses to work outfits.
They’re lightweight but still feel supportive enough for all-day wear, and I appreciate that they don’t require a break-in period. The fit is generally true to size, and the variety of colors makes it easy to stock up and rotate depending on the outfit.
Overall, these are reliable, easy-to-wear flats that offer great value for the price. Not flashy, just consistently comfortable and practical—which is exactly why I keep coming back to them.
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Reviewed in the United States on June 5, 2026
★★★★★ 5
Has the look that they should cost more.
Size: 11.5 Wide, Color: Dark Turquoise
Comfortable and the fit is very comfortable. Looks great and extremely comfortable. Soft and light weight. Easy to put on. Sizing was perfect and the wide width is truly a wide. I’m coming back for more colors.
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Reviewed in the United States on June 1, 2026
★★★★★ 4
Good at price
Size: 9 Wide, Color: Sand
Fit a little small at my big toe but otherwise fit well. Heel rubbed slightly first 5 hour wear but no blister.
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Reviewed in the United States on May 9, 2026
★★★★★ 5
Lightweight comfortable at a good price!
Size: 10.5, Color: Navy
These shoes are perfect. The color matches my navy outfits as well as my denim. They are comfortable and they look great. They are easy to pack lightweight and a great value.
I am extremely satisfied and highly recommend!
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Reviewed in the United States on June 3, 2026
★★★★★ 3
REALLY CUTE SHOE BUT CUT WAY TOO SMALL!
Size: 8, Color: Black Patent
I received the black patent leather shoes today and they are so cute! Sadly I need to return them because they are cut way too small. I normally wear a 7.5 or 8 on dress shoes so I ordered the 8. They are so tight across the top that it's uncomfortable as soon as I put them on. They are smaller than a normal size 8 dress shoe. The big toe area is extremely uncomfortable because it doesn't allow any room for it at all, so my big toe just presses against the side and end of the shoe without even walking in them. I have very narrow feet and these still are too small for me. So I am returning them and I already ordered a 8.5 W and hope that will fit much better. The patent leather is very cute and adds just enough dressy that I can wear them with slacks or my Capri jeans. I like the slip on and the cushion foot bed because it feels soft.
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Reviewed in the United States on May 26, 2026