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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
4.7 ★★★★★
Based on 21 reviews
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Product Reviews
★★★★★ 5
Good Ingredients, Tasty, and Convenient
Flavor Name: Beef Sticks - Original
Grassfed and good ingredients, these beef sticks taste good and are a great snack to have on hand. I like to bring a few along when I travel since I'm gluten free and can't always find something healthy to eat on the go. I highly recommend them.
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Reviewed in the United States on May 15, 2026
★★★★★ 5
The Perfect On-The-Go Snack!
Flavor Name: Beef Sticks - Original
I’ve tried countless meat sticks, but these 100% grass-fed beef sticks are in a league of their own. They have officially become my absolute favorite snack, and I make sure to always have a stash on hand in my pantry and gym bag.
What really sets these apart for me:
Superior Texture: Unlike so many other brands that are dry or tough to chew, these have the perfect amount of moisture and a "snap" that isn't rubbery.
Clean Ingredients: It’s hard to find a convenient snack made with such high-quality, grass-fed beef. You can really taste the difference.
Low Sugar: I love that I’m getting a protein boost without the hidden sugars and fillers found in most jerky products.
If you're looking for a quick, savory, and healthy snack that actually satisfies, look no further. Highly recommended!
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Reviewed in the United States on January 9, 2026
★★★★★ 4
Soft and delicious, but pricey (but worth it if you care about health)
Flavor Name: Venison Sticks - Original
Ugh, I wish these weren't so pricey, but I know it's because of the high-quality and I really do care about that. I'm willing to pay a bit more of grass-fed and finished meat. And these are the perfect quick snack. They're delicious, they're not hard and impossible to bite/chew like some meat sticks, and they give you clean nutrition. I didn't find them particularly greasy either. The packaging is impossible to open, but I wonder if I got a bad set - all of them are fully sealed at the top where normally there are two pieces so that you can peel the package open. All of mine require scissors to cut open which is frustrating but not the end of the world. Again, not sure if that's standard packaging or just a flaw on the ones I got. In any case, they are great and I have already repurchased!
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Reviewed in the United States on July 20, 2025
★★★★★ 5
DELISH
Flavor Name: Beef Sticks - Jalapeño
My entire family LOVES these meat sticks. You can taste the freshness. The texture is meaty, No greasy film, no nasty ingredients. I was sold after reading about the fermentation process of these meat sticks. Excellent flavor. I’ll never stop eating these. Jalapeño are my favorite, they aren’t too spicy.
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Reviewed in the United States on May 28, 2026
★★★★★ 5
Ten star quality and hands down the best I've ever had
Flavor Name: Venison Sticks - Original
I had a health practitioner suggest I increase protein intake and add in some game meats (venison, bison, elk) along with beef. I found Paleo Valley venison and beef sticks as a great solution to add these to my diet without a big bite in my budget. Paleo Valley provides several beef sticks that are all tasty and will appeal to a variety of consumer preferences though my personal favorite is the venison. All their sources are grass fed and finished, pasture raised and finished. You can instantly taste the difference in quality with your first bite. The sticks are firm and moist, nicely flavored and are simple to carry around as a quick snack or extra protein boost. I found I have less interest in sugary or carb-filled snacks by eating a quality protein source. Many other brands I've tried are hard, dry, heavily spiced and don't really taste natural. Not so with Paleo Valley. As a company, I found them to be very health conscious and have other supplements available, along with really useful educational tips for a healthier lifestyle. I think it's important to leave good reviews when I find something that's exceptional quality and Paleo Valley fits that bill.
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Reviewed in the United States on September 7, 2025