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For Your Every Summer RSVP, with Code: SUMMER15
Description
Holley HP EFI ECU and Harness Kits 550-604NHP ECU AND HARNESS, MPFI, NTK 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
HP ECU AND HARNESS, MPFI, NTK
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:
- 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
- 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 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
- Universal
Specs
| Brand | Holley EFI |
|---|---|
| Emission Code | 3 |
| Ignition Type | Coil - (No Timing Control) |
| Ford TFI | |
| GM HEI Small Cap | |
| Holley Dual Sync Distributor | |
| Injector Connector | Jetronic / Minitimer (Bosch) |
| Product Type | HP EFI Kit |
| Part Number | 550-604N |
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
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Product Reviews
★★★★★ 5
A portable power house built like a tank.
Style: Apple M5 Pro chip, Capacity: 24GB Unified Memory | 1TB SSD Storage, Color: Space Black, Set: Without AppleCare+
A well built powerful portable laptop computer with brilliant colors and a stunning 16 inch high definition screen. Consider your working space size as it is large and heavy: this portable is built to last with heavy use. Note, track pad is large, hands may cover right and left sides of touch pad while typing. There is not a part of this powerful device where production cost short-cuts were made sacrificing quality. The premium price for this Apple product is money well spent for dependable reliable blazing fast performance. Purchase this portable power house with confidence as it runs on the Apple operating system which is the envy of every global lap top competitor.
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Reviewed in the United States on April 29, 2026
★★★★★ 5
Great MacBook
Style: Apple M5 Pro chip, Capacity: 48GB Unified Memory | 1TB SSD Storage, Color: Space Black, Set: Without AppleCare+
The computer feels fast and smoothly, the screen quality is great, for me 1TB is more than enough. Not that suitable for portability purposes cause it is quite heavy.
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Reviewed in the United States on April 17, 2026
★★★★★ 5
Mac Pro = Worth It!
Style: Apple M5 Pro chip, Capacity: 24GB Unified Memory | 1TB SSD Storage, Color: Space Black, Set: Without AppleCare+
This Mac Pro completely changed the game for me. Absolute powerhouse. 🚀
No lag. No crashes. Just nonstop performance no matter how hard I push it — especially with AI workflows and multitasking.
I put this machine through heavy work every single day, and it handles everything effortlessly like it was built for the future.
Officially done with PCs. Apple really operates on another level. 🍎🔥
One VERY satisfied customer.
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Reviewed in the United States on May 19, 2026
★★★★★ 5
Space Black M5 Pro 48GB 1TB
Style: Apple M5 Pro chip, Capacity: 48GB Unified Memory | 1TB SSD Storage, Color: Space Black, Set: Without AppleCare+
I love this machine. I don't regret buying it at all. Screen is a little dim imo. It's very easy to use if your familiar with macOS I love how well it performs. The space black is gorgeous.
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Reviewed in the United States on April 24, 2026
★★★★★ 5
Perfect size and beautiful screen
Style: Apple M5 Pro chip, Capacity: 48GB Unified Memory | 1TB SSD Storage, Color: Silver, Set: Without AppleCare+
perfect, best laptop I have ever owned, whoever complains it is too big compared to the 14' really need to check up and go do some weight training. perfect size, incredible screen and barely weight more than the 14inch one.
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Reviewed in the United States on April 30, 2026
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