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Description
Holley HP EFI ECU and Harness Kits 550-603HP ECU AND HARNESS LS2 & LS7 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! Features: Simple Installation Plug and Play control of GM LS2 LS3 LS7 engines. Just plug the harness into
HP ECU AND HARNESS LS2 & LS7
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!
Features:
- Simple Installation - Plug and Play control of GM LS2/LS3/LS7 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, USCAR (EV6 Style) injector connectors, and Bosch wideband O2 sensor, designed to be used with GM LS2/LS3/LS7 engines with factory GM coils and a 58 tooth crank sensor
- 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" touch screen 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 | 58x |
| Emission Code | 4 |
| Ignition Type | GM LS 58x |
| Injector Connector | USCAR (EV6) |
| Product Type | HP EFI Kit |
| Part Number | 550-603 |
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
4.8 ★★★★★
Based on 29 reviews
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Product Reviews
★★★★★ 4
Good product , but
Size: 1.3 Fl Oz (Pack of 1), Size: 1.3 Fl Oz (Pack of 1)
It seems to be a good product and it’s not too heavy , but still caused few breakouts here and there . Also, Avenue always has protective foil on their cream , this one didn’t have (I replaced it but new one also didn’t have it). Also, it goes away really fast because it’s only 1.3 ounces.
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Reviewed in the United States on April 12, 2026
★★★★★ 5
Hydrating
Size: 1.3 Fl Oz (Pack of 1)
Dermatologist recommended. Works very well
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Reviewed in the United States on May 16, 2026
★★★★★ 5
Gold Star
Size: 1.3 Fl Oz (Pack of 1)
This cream is truly gentle and healing for a compromised skin barrier. I prefer this cream in the winter, when the weather is dry, and after procedures like microneedling or laser. It has never irritated my skin, and does soothe and heal. The La Roche Posay cicalfate cream is also excellent, I think it is slightly less rich, so I prefer that in humidity or the summer.
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Reviewed in the United States on March 2, 2026
★★★★★ 5
Overpriced but it works.
Size: 1.3 Fl Oz (Pack of 1)
I hate that I love this product. It's stupid expensive. But it's great for broken/damaged/recovering skin. I've used it post microneedling and it is the only thing that soothes, hydrates, and doesn't sting raw, red skin. Great for rashes/hives and allergic reactions too. Luckily a thin layer is often enough to do the trick. so it lasts a long time I wouldn't use for everyday moisture, but when your skin is angry, this stuff works. (Overpriced? Yes. Witchcraft? Maybe. Does it work? Yep.)
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Reviewed in the United States on December 10, 2025
★★★★★ 5
Works wonder
Size: 1.3 Fl Oz (Pack of 1)
Amazing product. The scars from my daughter acne are mostly gone after 1 month. We will purchase again
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Reviewed in the United States on February 27, 2026