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Description
HP EFI ECU & Harness Kits - 550-603NOverview: 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
Overview:
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 NTK wideband O2 sensor, designed to be used with GM LS2/LS3/LS7 engines with factory GM coils and a 58 tooth crank sensor
- The NTK Oxygen Sensor is recommended when using leaded or methanol fuels, high exhaust 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" 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:
| Year | Make | Model | Submodel | Engine Size |
|---|---|---|---|---|
| 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 |
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
4.7 ★★★★★
Based on 17 reviews
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Product Reviews
★★★★★ 4
Very comfortable, fits nicely with my not-so-flat tummy, gorgeous color
Color: Blue, Size: XX-Large, Color: Blue, Size: XX-Large
This is a very comfortable shirt. It feels cool when you wear it and it's slinky soft against your skin. It arrived with fold marks, but those fell out nicely after a few hours hanging. So this is a no-iron shirt for sure, which I love. I haven't tested the stain shield claims but am familiar with this material so I believe it will resist stains. It does dry quickly when damp.
I love the blue color I chose. It's bright and cheerful but not tacky. The photos I posted are pretty close. The material is thick and feels like quality fabric. The stitching is single-stitch, which makes me feel that it's maybe not as durable as double stitched or crossover stitched hems. But regardless, the stitching is tight and the hems are even. The button holes durable and the firmly sewn buttons match the fabric very closely.
The fit is very nice. I'm a bit stout, so slim fit shirts are too tight across my stomach if they fit in the shoulders, or too loose in the shoulders if they fit my middle. The cut of this shirt is a good compromise and it looks very nice. And the slight stretch of the fabric makes it very comfortable when I'm moving around. The collar is stiff enough to sit nicely and not flop too much.
This shirt is great for casual wear but looks nice enough for a more dressy situation. I think it's a good price for a very nice shirt.
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Reviewed in the United States on February 12, 2026
★★★★★ 5
Nice shirt
Size: Large, Color: Green
Cool shirt, great blended colors. Fit is great.
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Reviewed in the United States on May 30, 2026
★★★★★ 5
Nice shirt, great price
Size: Large, Color: Royal Blue
Very nice shirt. Has a soft, flowy (?) hand to it. Not starchy like a lot of oxford button-down collar shirts. Second one I’ve bought. Nice
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Reviewed in the United States on May 21, 2026
★★★★★ 5
Great shirts.
Size: X-Large, Color: Black
I have 10. These are great, stylish shirts especially for the price. I usually wear between size L-XL slim fit (Banana Republic). I’m 6’ 200 lbs medium athletic build and L fits perfectly. With a quick press, they do not wrinkle easily. I get plenty of compliments.
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Reviewed in the United States on April 24, 2026
★★★★★ 4
Runs large, not slim fit
Size: Medium, Color: Green
The shirt definitely runs large like all the other reviews say. I usually wear a large, but the medium fit much better. The shirt is definitely not slim fit though.
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Reviewed in the United States on April 3, 2026