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Description
Holley 550-903T EFI Terminator X - GM LS1/LS624x Crank 1x Cam EV1 Injectors USB CAN Tuning Cable Part Number: 550 903T Take control of your LS engine with Terminator X! Don't settle for a junkyard ECU with a cumbersome tuning interface when you can have complete control of your engine, self learning fuel strategies and the proven, race winning technology of Holley EFI at a budget friendly price! Terminator X features real time fuel learn, high impedance injector drivers, an integrated 1bar MAP
24x Crank - 1x Cam - EV1 Injectors - USB/CAN Tuning CablePart Number: 550-903T
Take control of your LS engine with Terminator X! Don't settle for a junkyard ECU with a cumbersome tuning interface when you can have complete control of your engine, self-learning fuel strategies and the proven, race-winning technology of Holley EFI at a budget-friendly price! Terminator X features real-time fuel learn, high impedance injector drivers, an integrated 1bar MAP sensor, and 4 programmable inputs and outputs. The inputs and outputs are ideal for electric fans, boost control solenoids, progressive nitrous control, and much more. Terminator X comes fully loaded with base maps for common LS engine combinations to get you out of the garage and on the road/track fast. These Terminator X kits include a USB/CAN tuning cable instead of the 3.5" Handheld LCD, these kits require the use of the free Terminator X Software for initial setup. The Terminator X Software includes multiple base calibrations to choose from for either naturally aspirated or boosted engines. Also included is Holley EFI's industry-leading, easy to use software suite that allows full laptop access for advanced users. Whether you are building a budget beater or a boosted race car, Terminator X has the features and technology you need at a price that won't break the bank!
Features and Benefits
• For GM LS1/LS6 engines with 24x crank reluctor - with EV1 Injectors.
• Real-Time fuel map learn, takes the guess work out of tuning your base fuel table.
• High Impedance Injector Drivers will safely power most Stock LS injectors, and Holley EFI Injectors. Injector support chart provided in the instructions (Will not control Low Impedance Injectors)
• All of the new Terminator X systems utilize the Bosch LSU 4.9 wideband to relay AFR information to the ECU for accurate reading and precise tuning control.
• On-Board 1bar MAP sensor, is perfect for N/A or Nitrous engine combos. If your combination requires a 2+Bar, we recommend GM 12592525, and our adapter part number 558-416.
• MAP Sensor vacuum hose adapters (1/8th – ¼ and 3/16ths)
• 4 Inputs – 12v, Ground, 5v, and Frequency, for things such as additional pressure sensors, or activation triggers for nitrous activation, or a trans brake
• Boost Control – Boost vs Time, Boost vs Gear, Boost vs RPM, Boost vs Speed, Boost Safeties
• Nitrous Control – Single Channel of Wet or Dry, Progressive or Non-Progressive, Rich/Lean Safeties, and target Closed Loop AFR
• Advanced Tables – 4x 1D Tables, 1x 1D per Gear Table, 4x 2D Tables, 1x 2D per Gear Table, can be used for any custom tables you can dream up, such as Flex Fuel Sensor Offset Table, or a custom fuel or oil pressure safety!
• On-Board Diagnostic LEDS for: ECU Power – Engine Run – Wideband Status – TPS Calibration – Crank Signal –Cam Signal. Allow you to identify any Critical engine issues at a glance
• Includes CAN/USB tuning cable allowing you to configure your ECU and Tuning the engine in real time.
• The compact ECU size allows you to mount it virtually anywhere. Remember, diagnostic LEDS must face up!
• Plug and play compatible with multiple Holley EFI accessories including our gauges, shift lights, various modules, and digital and pro dashes (Holley P/N's 553-106, 553-111, and 553-112)
• Free EFI Tuning Software for complete control of your Terminator X power plant
• Includes: 24x LS Engine Main Harness - EV1 Injector Harness - Terminator X ECU - ECU Main Power Harness - Bosch LSU 4.9 Wideband Oxygen Sensor - Input/Output Harness - and assorted vacuum adapters.
Terminator X ECU's are designed to be mounted with the LED's facing up.
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
4.3 ★★★★★
Based on 12 reviews
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Product Reviews
★★★★★ 5
Very nice vest.
Color: Black, Size: 4X-Large
Color- Black
Size: 4X-Large
Bought for my sons 12 grade events. It is a nice lookiing vest he wanted to wear with his dress clothes.
It fit him beautfully. He was able to bo up the buttons with out any issues
Decently priced. It felt nice on and is dressy without being to dressy so he will get some more use out of it other then school events.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on February 25, 2026
★★★★★ 4
Very stylish and fit
Color: Navy Blue, Size: Large
Perfect for work, very affordable for a waist cost. Detail and quality are great
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 14, 2026
★★★★★ 5
Nicely made
Color: Black, Size: X-Large
Well made and looks like I paid several hundred dollars for it. Really dressing up a nice pair of jeans and white dress shirt.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 30, 2026
★★★★★ 5
Nice vest at a good value
Color: Black, Size: Large
Nice vest out of the bag. Fit is good. I’m 5’10” 200lbs with a bit of a beer belly. I’m not muscular at all. Use that description as a comparison to your own body. I can’t speak to the overall quality and how long it will last but for my use going to a black tie gala this is a really nice vest. Happy with my purchase.
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Reviewed in the United States on March 9, 2026
★★★★★ 3
Mixed Review. Let me explain.
Color: Black, Size: Large
I ordered both the light gray and black vests in Large. Each one was delivered separately, not sure why, but a day or to late on one was no big deal. I got the gray vest on time. Label reads "COOFANDY." Fits perfectly. The black vest arrived late. Label reads "PAUL JONES Since 1958." Vest was too small. A different material was used on the back section of the vest, which is common, but not what I wanted. The gray vest was constructed of the same material used on the front. I'm not sure if this was a packing error or what, but I returned the black vest for a refund. The verdict: Great, well-constructed, true fit vest with the COOFANDY label. Not so well-constructed (a couple of the button holes had loose threads), small fit vest with the PAUL JONES label. Be sure to check that label. Five stars for the COOFANDY minus two stars for the goofed-up quality control of the seller.
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Reviewed in the United States on December 13, 2019
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