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- USA
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Ships within 48 hours · Estimated delivery Jul 15 - Jul 20
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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
4.8 ★★★★★
Based on 1431 reviews
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Product Reviews
★★★★★ 5
Stunning Automatic Watch With TopTier Durability and Precision
Color: Grey
“I got this Tissot PRX for my cousin’s birthday and bro fell in LOVE instantly.
This thing keeps time like a beast, never slows down, never lags. Automatic movement, so no batteries, no drama.
Durability? Stupid good. You can hit it, bump it, live life rough, it still looks box fresh.
Size wise it was almost perfect. I just had to remove two links, nothing big.
It’s light, functional, comfortable, doesn’t weigh you down, doesn’t get in the way but more importantly I can say this watch is in everyone’s eyesight when we wear it. Cause of course I had to get another one!
Basically. I gave him a very nice piece as a gift, and now he’s walking around like he owns Switzerland.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on December 11, 2025
★★★★★ 5
Great watch!!!!
Color: Grey
Excellent quality, one of the best, elegant.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 6, 2026
★★★★★ 5
Excellent value for an automatic watch, keeps VERY good time.
Color: Grey, Color: Grey
I've only had the watch for a day but wanted to leave a quick review on it to share a couple of notes.
So far it keeps VERY good time, better than any of the automatics I own (including a Rolex Submariner, Tag Heuer Aquaracer, Tag Heuer Formula One, and several other sub $1k watches). I set it to an atomic time app on my phone yesterday and 24 hours later it's still SPOT on - hasn't gained/lost even a 1/10 of a second. I was shocked to see it's kept PERFECT time for the last day, I'm really blown away so far. I've worn it the entire time, we'll see how well it keeps time while being stored in a winder.
This picture shown is the watch with a 22mm leather band on it, fit's without any issues (just need to squeeze in the leather a tad). I doubt it would work with a 22mm metal bracelet, but leather works great. Just FYI since the 21mm lug width is kind of odd.
The face isn't quite a lustrious as the images make it look, but it's still a great-looking watch. For a sub $1000 automatic you can't go wrong, this is a fantastic watch at a great price. It'll be my daily driver for some time I'm sure. If I have any issues in the future I'll update the review.
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Reviewed in the United States on March 22, 2021
★★★★★ 5
It looks really cool and striking.
Color: Grey, Color: Grey
Really cool and beautiful watch. Although my specific unit runs 5 seconds fast every day—at first it’s annoying, but eventually you stop caring. 🤣
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Reviewed in the United States on April 16, 2026
★★★★★ 5
A Beautiful Timepiece at an Awesome Price!!
Color: Grey, Color: Grey
I have lusted after this watch for four months. I first tried on a similar model (stainless steel band with a green face) in a local jewelry shop (Spitz Jewlers, Walnut Creek, CA, USA). It was "love at first sight," even if I didn't love the white lines on the face from 12-6 and 3-9. At the time, the MSRP was $775.
The MSRP has since increased to $795. But I bought this beauty on Amazon.com for only $524.99; after applying the cash-back from my Prime credit card, this watch costs only $498.75. This was "the offer that I could not refuse," to quote from "The Godfather."
Accuracy could be better: after only a few days, it is now 7 seconds behind my phone (to which I set my new watch). But I don't really care about that all that much. This is why I rated "accuracy" at 4 stars, but my overall review is 5 stars.
My video shows the date changing suddenly at 11:59:59pm, just how I want it; in another photo, you can see that my Seiko changes the date more slowly, which I do not like.
This watch is absolutely phenomenally beautiful. If you're on the fence over whether to make this purchase, then I would say "go for it!" You will not find a prettier, more accurate watch at a lower price in ANY store in the entire USA.
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Reviewed in the United States on April 28, 2023
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