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Description
Holley HP EFI ECU and Harness Kits 550-606FORD MPFI HP ECU AND HARNESS KIT Looking for a alternative for your stock or built late model factory FORD 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
FORD MPFI HP ECU AND HARNESS KIT
Looking for a alternative for your stock or built late model factory FORD 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
- 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 tu
Application
-
Universal
Specs
| Brand | Holley EFI |
|---|---|
| Emission Code | 3 |
| Ignition Type | Coil - (No Timing Control) |
| Ford TFI | |
| Holley Dual Sync Distributor | |
| Injector Connector | Jetronic / Minitimer (Bosch) |
| Product Type | HP EFI Kit |
| Part Number | 550-606 |
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
4.6 ★★★★★
Based on 14 reviews
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Product Reviews
★★★★★ 4
Heavy linen character, but a beautifully tailored suit!
Color: Beige, Size: 4, Color: Beige, Size: 4
This is a really nice linen suit! The jacket is beautifully made and well-tailored, with a fun speckled texture that has lots of pretty color variation (we ordered the beige). When I placed it side by side with a similar linen suit from another brand, the difference in the linen texture was really noticeable — this had a much stronger linen character that stands out!
It has three useful pockets on the outside of the jacket, which is great for little hands. The only downside is that one of the inside pockets is just for show (faux), which was a bit surprising and somewhat disappointing for my little guy.
The pants have pockets too, but they aren’t very deep — perfect for small treasures, but not much more. The pants are made from a lighter, thinner single-layer linen compared to the fully lined, double-layer jacket, which makes sense for comfort and easy movement.
The pants didn’t come with a front crease ironed in, so you’ll want to press one yourself. The linen did pick up some creases from being folded in the package, but it doesn’t seem quite as wrinkly as some other linen fabrics I’ve tried. Still, like most linen clothes, especially for boys, the pants will need occasional ironing to keep them looking neat and crisp, especially after a day of play and general wear. The structured, lined jacket stays looking smoother and more put-together with less effort.
It also came with a bow tie, a neck tie, and a tuxedo-style white shirt as extras. The ties aren’t great quality — they’d work fine for quick photos but probably won’t hold up to much actual wear. The formal white shirt feels a bit funny paired with the casual linen suit, but I don’t mind at all. We already have white shirts that we prefer, so we’ll use those instead. For us, the extras are really just bonus items we won’t plan on using.
Overall, it’s a handsome little suit that’s perfect for special occasions like weddings, family photos, or holiday events. My kid looked adorable in it! The stronger linen texture on the jacket gives it a premium feel that I really like. Just be ready for a bit of extra care with the pants to keep everything sharp.
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Reviewed in the United States on April 8, 2026
★★★★★ 5
Great suit set
Color: Light Grey, Size: 4
It is incredibly attractive and includes everything a young child needs for a special occasion.
The material is a 75% polyester and 25% linen blend, and the outer fabric feels remarkably smooth. Its unstructured design allows for an attractive, natural drape, and the blend conveniently allows for machine washing at home.
As is typical with linen-based materials, the fabric can be naturally stiff and prone to wrinkling, so I recommend ironing or steaming it before use. The lightweight feel makes it an excellent choice for the spring, summer, and fall months.
Overall, this suit offers exceptional value for the price.
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Reviewed in the United States on April 12, 2026
★★★★★ 5
Summer wedding kids suit
Color: Navy, Size: 10 Years, Color: Navy, Size: 10 Years
Bought this suit for my son in the 10 youth size and honestly was pleasantly surprised by the quality for the price. The navy color looks sharp and dressy without being too stiff or uncomfortable. The material has a little stretch, which helped it fit nicely and made it comfortable for him to move around in.
The adjustable waist was a huge plus, especially for growing kids. It fit true to size overall, though the blazer sleeves were slightly long on my son. The pants had a nice slim look without being too tight. We paired it with white sneakers for a more modern look and it came out adorable.
This would be perfect for weddings, graduations, concerts, communion, school events, or family photos. Overall, very happy with the purchase and would definitely buy again.
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Reviewed in the United States on May 18, 2026
★★★★★ 5
Very Modern Handsome Suit
Color: Grey, Size: 7 Years, Color: Grey, Size: 7 Years
This is an incredibly sharp looking suit for the little guy. Great price and features, too. I made a mistake in sizing up instead of down and first one was too sloppy on him and would need alterations. He is thin and very thin in the waist. There is a lot of adjustment with buttons in waistband and coat hides the bunching. This shirt and coat will easily take a fuller body than slim I believe. He loves posing in it and feels very classy. Best purchase for a formal suit that will last longer than most kids clothes size wise. Felt bad about returning but careful folding and packing got it good as new.
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Reviewed in the United States on May 20, 2026
★★★★★ 5
Quality
Color: Black, Size: 7 Years, Color: Black, Size: 7 Years
Excellent quality, My son looks incredible
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Reviewed in the United States on June 5, 2026