SKU: 33339934358

Holley HP EFI ECU & Harness Kit (HO550-605)

$2633.85 $2926.50
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Description

Holley HP EFI ECU & Harness Kit (HO550-605)HO550 605 HP EFI ECU WITH UNTERMINATED Unterminated Universal Harness Part Number: HO550 605 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

HO550-605 - HP EFI ECU WITH UNTERMINATED

Unterminated Universal Harness

Part Number: HO550-605

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.
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

Shipping Notes
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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]
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SKU: 33339934358

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4.5 ★★★★★
Based on 30 reviews
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Verified Purchase
D. Smith
San Leandro, US
★★★★★ 5
Hands down, the BEST handheld frother I've ever used!
Color: Black
Hands down, the BEST handheld frother I've ever used! I got the black one, but any color will have the same results. Over the past 12 years or so, I've used so many different handheld frothers and they've ALL fallen short of expectations for quality, longevity, power, features, and usability. I've used everything from cheap, $15 models to $50+ models and everything in-between. Some with fancy attachments for various types of mixing, frothing, beating, whipping, etc. Some with rechargeable batteries, some without. Some AC powered, some with fixed whisks, some with detachable/replaceable whisks, some with stands, etc. NONE have been spectacular. Most broke within 6 months and got tossed. ALL were major disappointments in the end, including the "revered" Zulay models of which I tried several. I finally found this Maestri House branded, variable speed frother with detachable / replaceable whisks and got one to try. I was literally on Cloud Nine the first time I turned it on. Like, WOW! Not only was it FAST on the highest speed, but it was powerful enough to churn right through milk, eggs, cream, etc, without bogging down like many others. This thing makes milk froth like a milkshake and Matcha Lattes like nothing else I've ever experienced. I used to have to sift my Matcha, then whisk it in hot water, then froth milk and then blend them together to make the perfect latte. and if the milk was cold (my preference), pre-whisking in hot water was a must to avoid lumps. However, with THIS frother? I literally pour my milk into a tall tumbler, drop in un-sifted Matcha powder, and spin up the Maestri House frother at first on a medium low speed to get it mixed, then jump straight to the highest speed to really whip that milk and match up. After about 30-45 seconds, I've got the thickest, richest, smoothest, most aerated latte around. And NO LUMPS at all!!! What a time and dish saver! And cleaning? I just run it under hot running water to get the shaft cleaned and then spin it up in a dish with hot running water for a few moments, then spin it on high for a few seconds in the air to dry it off instantly. Now, I'll be honest here, too. The specs say it can go months on a charge, using it for a couple minutes a couple times daily. Well, I guess it could do that and still spin. But I use it FULL SPEED, churning hard for at least a minute a couple times per day. After about 2 weeks, I can start to notice a speed reduction so I just plug it back in on the charger. All things considered, this is still better than all the other handheld frothers I've used over the years. After using the heck out of this thing for the past 7 months, I've even decided to start selling these in our Japanese gift shop. The manufacturer is has been very responsive both in customer support (I called them about an issue I thought I was having, and they called me back with a couple hours even though I didn't leave voicemail when they didn't answer right away) and in reseller support. I have to give these guys an A+ for responsiveness and quick resolution when problems might arise. HIGHLY recommended!!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on October 17, 2025
H
Verified Purchase
Hawaii Keith
Port Orchard, US
★★★★★ 5
Great Addition!
Color: Black
Why did you pick this product vs others?: I just started a powdered drink routine recently and was having a difficult time mixing it with water. I would consistently end up with small nuggets of mix making it unenjoyable to drink. I knew I needed a mixer and was glad I found this device when I did. It works perfectly! I like the fact that it comes with its own stand and included two mixing heads. It is solid, well-designed, and you can feel the quality when you pick it up. The variable speed of the mixer is perfect for ensuring that everything is blended well. I haven’t used it to “froth” anything yet, at least not on purpose, but I accidentally found out that it can do that well. This is a great addition to our kitchen and is very easy to wash after use. So far…no issues. Highly recommend for those of you looking for the right tool to make sure those protein mixes aren’t full of unmixed nuggets.  
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on June 21, 2025
S
Verified Purchase
Suzi blue
Lexington, US
★★★★★ 4
Low foam
Color: Black
Love this frother. It is great quality and the turn speed is amazing. My only issue is this. It comes w 2 wands and they are both singles. The single is great for stirring things up. It does not make a lot of froth and for some things it’s perfect but sometimes I like a lot of froth and I wish it either came w a single and a double or you could purchase a double separately to intermix. I don’t want to buy a whole other unit just for the double. I wrote to them bc the double frother they sell doesn’t look as good as this one but sometimes a girl needs a lot of foam and sometimes th stirring is perfect.
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Reviewed in the United States on February 20, 2026
A
Verified Purchase
Alan Smithee
Los Angeles, US
★★★★★ 5
Strong and Quiet
Color: Lux Cardinal Red, Size: Rechargeable Z1 Motor Max
Better than I expected. Works in two modes. Makes mixing a breeze.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 23, 2026
K
Verified Purchase
Kindle Customer
New York, US
★★★★★ 5
Powerful!
Color: Lux Galaxy, Size: Rechargeable Z1 Motor Max
This thing is powerful and works great! I was hesitant about some of the negative reviews, but this is worth it so far. I use it every day and haven't charged it in the week that I've had it. Some people complained about turning it off.... It's not that hard. Just hold the button down for a second or two and it shuts off, no fuss. If you tap/press the button you'll cycle through the next speed and then off. I only use the first speed to make my protein shake and matcha. I feel like the high speed would just whip everything to pure foam! I'm hoping this lasts me a long time.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 5, 2026

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