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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
4.6 ★★★★★
Based on 14 reviews
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Product Reviews
★★★★★ 5
My dogs favorite toy EVER
Color: Crinkle Chicken (Brown), Size: Large
I have a Belgian Malinois who loves any and every toy, but this one is definitely her favorite. She will walk around the house constantly carrying it in her mouth, which is honestly adorable to watch.
The squeakers only lasted a couple of months, but I don’t really consider that a downside—I’m kind of grateful they didn’t last forever given how much she plays with it. It still remains one of her most-loved toys even without them.
My only word of caution is that if you work from home, this toy makes a lot of crinkling noise. And I mean A LOT. It’s great for keeping the dog entertained, but it can definitely get a little frustrating for humans trying to focus or take calls.
Overall, it’s been a big hit in our house and easily one of her favorite toys.
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Reviewed in the United States on June 8, 2026
★★★★★ 5
Super cute
Color: Bunny (Mauve), Size: Small
Super cute and fuzzy. Definitely perfect size for a puppy and not too loud. The fur is very soft and the nose is sown on not a hard piece that can be chewed on. Very good quality too.
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Reviewed in the United States on June 3, 2026
★★★★★ 4
Normally amazing
Color: Spiky Ball (Blue, Orange), Size: Medium
We have purchased these slightly spiky dog balls several times for our very strong jaw heavy chewer dogs and they’ve been amazing. They don’t break down they don’t get torn apart the squeakers don’t even pop out of them.
So we ordered another package because we’ve lost a few outside to the lawnmower… oops and the package that got delivered today had only one ball that squeaks and the other does not. THIS IS A PROBLEM ! Unfortunately my female dog got to the new squeaking ball first and my male got to the non-squeaking ball and he was NOT happy. Basically once they claim a ball it’s theirs and the other dogs don’t go near the ball they claimed. So he’s following my female around and every time she squeaks the ball and I’m just waiting for him to attempt to take it from her causing damage to her. Normally… These are amazingly fun, tough, durable but also squeaking balls (that’s rare in a tough ball) that my dogs absolutely love.
This time just got a bad batch I guess. When they squeak the dogs LOVE them. After several months of play the squeaker might break inside of the ball but the ball never comes apart or gets damaged. And we as the owners love that they don’t break down are not able to be ripped or torn even by our very strong jawed and big jaw muscle dogs.
They are also great for in the house play because they’re small enough that they fit completely inside our dog‘s mouth but obviously not small enough to get swallowed so when we throw them in the house for fetch the dogs can jump up and catch them fully in their mouth so they don’t cause any damage to the walls when they hit the walls. They’re not super heavy but they’re incredibly durable.
Definitely worth the price especially if you have heavy chewers or big jaw muscle dogs.
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Reviewed in the United States on April 28, 2026
★★★★★ 5
Best fun indestructible toy
Color: Crinkle Duck (Yellow), Size: Large
Truly indestructible no matter how much our oittie tries. She has owned it for three months works at destroying every day with no success. She carries it everywhere. Best purchase for chewer, more fun than the popular rubber heavy duty toy. Do not hesitate your pup will thank you for this fun distraction.
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Reviewed in the United States on May 30, 2026
★★★★★ 5
My dog loves this toy!
Color: Bunny (Gray), Size: Large, Color: Bunny (Gray), Size: Large
High quality, big toy, perfect for a medium to large size dog. After a few months of serious chewing I had to buy another one, but well worth the money! Rocky loves it.
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Reviewed in the United States on June 11, 2026