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- USA
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Ships within 48 hours · Estimated delivery Jul 7 - Jul 12
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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
4.9 ★★★★★
Based on 1991 reviews
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Product Reviews
★★★★★ 5
No after taste
Flavor Name: Peppermint
Easy on digestive system
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on July 16, 2025
★★★★★ 5
Excelente
Flavor Name: Peppermint
Excelente
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Reviewed in the United States on January 4, 2026
★★★★★ 5
Holy dreams Batman!
Flavor Name: Peppermint
This product is so good I had to come back to review it! I originally got this for my daughter since she has terrible insomnia, but she hated the minty taste...so I started taking them along with my husband and wow is all I have to say! It makes me tired and I’ve been having the craziest dreams (I usually never dream or remember them)! Definitely recommend and I actually really like the flavor.
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Reviewed in the United States on December 9, 2020
★★★★★ 3
Not fast dissolve. After 20 minutes, it still sits beneath my tongue.
Flavor Name: Peppermint
This is definitely not fast dissolving tablets. My B12 and biotin sublingual tablets dissolve in a couple of minutes but these pills last over 20 minutes.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on March 8, 2022
★★★★★ 5
Good supplement for uric acid support
My dad has been using this support supplement for uric acid for a while and I thought it was a good option. The ingredients feel of quality and are easy to take, as the capsules are of adequate size and do not cause stomach discomfort.
I like that it is also focused on kidney support and that it does not have a strong taste or noticeable side effects in my case. It is a convenient alternative to complement a balanced diet and healthy habits.
The value for money is good and the packaging performs a lot. In general, I am satisfied with the product and would buy it again.
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Reviewed in the United States on February 26, 2026