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Description
Holley HP EFI ECU and Harness Kits 550-602NHP ECU AND HARNESS, LS1 6, NTK Looking for a plug and play kit for your GM LS engine? The HP ECU allows you to accurately control the fuel and ignition of your engine plus much more! Got a stock LS engine? Simply download a base map and you're on your way. Got a turbocharged, nitrous fed LS engine on water meth? This HP EFI kit can control that too! Stop reflashing your factory ECU every time you make a performance modification. Get Holley EFI today!
HP ECU AND HARNESS, LS1/6, NTK
Looking for a plug and play kit for your GM LS engine? The HP ECU allows you to accurately control the fuel and ignition of your engine plus much more! Got a stock LS engine? Simply download a base map and you're on your way. Got a turbocharged, nitrous fed LS engine on water/meth? This HP EFI kit can control that too! Stop re–flashing your factory ECU every time you make a performance modification. Get Holley EFI today!
Features:
- Simple Installation - Plug and Play control of GM LS1/LS6 engines. Just plug the harness into your factory sensors, wire the power and grounds and you are ready to take complete control of your LS engine
- More Functionality - Provides significantly more functionality than OEM or other competitive ECUs (boost control, nitrous control, water/meth injection, plus a host of additional inputs and outputs to control fans, pumps, relays etc.)
- Easy To Use - Laptop programmable ECU includes a variety of base maps that will have you hitting the cruise or track in no time
- Ideal For Everything - including stock 5.3L engine swaps or all out, 3,000+ horsepower race cars that need a simple and powerful ECU and harness solution
- Industry Leading Self Tuning Fuel Strategy - means less time tuning and more time enjoying the power of your LS vehicle
- Kit includes ECU, harness, communication cable, software and and NTK wideband 02 sensor designed to be used with GM LS1/LS6 engines with factory GM coils and a 24 tooth crank sensor
- The NTK Oxygen Sensor is recommended when using leaded or methanol fuels, high exhaust temperatures and forced induction applications or for highest precision feedback
- ECU is fully potted and can be mounted in the engine compartment or interior
- Sealed automotive and marine grade connectors
- 1-5 Bar MAP sensor capability
- Optional plug and play hand-held programmer, 5.7" touchscreen and digital gauges are available for ultimate control and vehicle monitoring
- ECU is certified to ISO 8846, SAE J1171 & United States Coast Guard Requirements for Ignition Protection & Fire Resistance
- For a full list of advanced features such as boost, nitrous, water/meth, individual cylinder control and more click the document icon under the product image!
Application
- Universal
Specs
| Brand | Holley EFI |
|---|---|
| Crank Reluctor | 24x |
| Emission Code | 4 |
| Ignition Type | GM LS 24x |
| Injector Connector | Jetronic / Minitimer (Bosch) |
| Product Type | HP EFI Kit |
| Part Number | 550-602N |
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
4.4 ★★★★★
Based on 12 reviews
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Product Reviews
★★★★★ 5
Long lasting and safer alternative to sticks
Color: Dogwood & Calming, Size: Medium
These are great, very durable, and have lasted a very long time. Much safer for my dogs than the random sticks they find in the yard. They do get shorter with chewing eventually, but they don't break off in little chunks like I've seen with some nylon chews, and they don't splinter like wood. Medium size works well for both my 16 lb Cavalier and my 60 lb Pyrenees/Golden mix. They're both moderate-to-aggressive chewers, though size obviously affects how much damage they can do.
I wish you could buy the hemp chew separately because that one is very much a favorite in my house, so after 2 years and 2 purchases, I have barely any left of the remaining hemp chew, but still 2 of the dogwood chews that neither dog is as interested in anymore. I'd love to buy a couple more of just the hemp one.
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Reviewed in the United States on April 30, 2026
★★★★★ 5
Your dog will thank you.
Color: Dogwood & Fresh Breath, Size: Large
My dogs loves to chew on these. They make a small mess but not as bad as other chews. They are food for keeping teeth clean.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 31, 2026
★★★★★ 5
Nice chew toy
Color: Dogwood Mushroom, Size: Medium, Color: Dogwood Mushroom, Size: Medium
Super durable and puppy loves it. It was a bit hard for her at first but now at 5 months it’s one of her favorite things to gnaw on! It is heavy for the size but seems to be great quality and has given many hours of chew time with minimal wear.
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Reviewed in the United States on March 12, 2026
★★★★★ 4
Long lasting
Color: Dogwood & Calming, Size: Medium
My dogs love these bones.
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Reviewed in the United States on March 25, 2026
★★★★★ 5
Puppy loves these sticks!
Color: Dogwood & Calming, Size: Medium
Dogs love these sticks! Must smell and taste like real wood because it keeps my puppy from bringing real sticks in the house from outside. She is a heavy chewer and these sticks keep her occupied. We are on our 2nd set.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 27, 2026