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- USA
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Ships within 48 hours · Estimated delivery Jul 11 - Jul 16
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Description
Holley Terminator X MAX Engine Management Systems 550-917TERMINATOR X MAX MPFI W TRANS CONTROL Take control of your LS engine with Terminator X Max! 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 Max features real time fuel learn, high impedance injector drivers, an integrated 1bar MAP sensor, and 4 programmable
TERMINATOR X MAX MPFI W/TRANS CONTROL
Take control of your LS engine with Terminator X Max! 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 Max 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. Part number 550-917 also has 4L60E or 4L80E Transmission control. Terminator X Max comes fully loaded with base maps for common LS engine combinations to get you out of the garage and on the road/track fast. The 3.5" touch screen LCD handheld contains an easy to use calibration wizard as well as tuning and gauge display functions. 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 MAX has the features and technology you need at a price that won't break the bank!
Features:
- For GM LS 4.8/5.3/6.0 Truck Engines with 24x crank reluctor, Transmission Control, and Multec 2 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 Max 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
- 4 Outputs – Ground, PWM - , for accessories such as; fans, boost control, nitrous control, IAC Kit, and More
- 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 AFRadjustable through included 3.5” full color touchscreen, base tune easily created via handheld Wizard!
- 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
- The included 3.5" Touchscreen Handheld contains a calibration wizard, that allows you to quickly build a base tune for any LS engine. Additionally the handheld provides internal data-logging and a fully customizable gauge display.
- The compact ECU size allows you to mount it virtually anywhere. Remember, diagnostic LEDS must face up!
- Plug and play compatible with more Holley EFI accessories such as; analog style gauges, shift lights, various modules, and coming soon, 12.3" digital dash support!
- Free EFI Tuning Software for complete control of your Terminator X power plant
- Includes: 24x LS Engine Main Harness - Multec 2 Injector Harness - 4L60E/4L80E Transmission Control Harness - Terminator X MAX ECU - ECU Main Power Harness - Bosch LSU 4.9 Wideband Oxygen Sensor - Input/Output Harness - and assorted vacuum adapters.
Application
- 2003 - 2006 Chevrolet Express
- 2003 - 2006 GMC Savana
- 1999 - 2006 Chevrolet Silverado
- 1999 - 2006 GMC Sierra 1500
- 2000 - 2006 Chevrolet Tahoe
- 2000 - 2006 GMC Yukon
- 2002 - 2007 Chevrolet Avalanche
- 2002 - 2006 GMC Yukon XL 1500
- 2003 - 2005 Chevrolet TrailBlazer EXT
- 2003 - 2004 Isuzu Ascender
- 2003 - 2004 GMC Envoy XL
- 2003 - 2004 Chevrolet SSR
- 2004 Buick Rainier
- 2002 - 2007 Chevrolet Silverado 1500
Specs
| Brand | Holley EFI |
|---|---|
| Crank Reluctor | 24x |
| Emission Code | 3 |
| Ignition Type | GM LS 24x |
| Injector Connector | Multec 2 |
| Product Type | Terminator X Max LS MPFI |
| Terminator LS Options | Fuel, Spark, Transmission |
| Part Number | 550-917 |
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
4.5 ★★★★★
Based on 2279 reviews
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Product Reviews
★★★★★ 5
Nice chair
Easy to assemble and looks clean in my home office. The lumbar support is actually helpful, and I like that the arms flip up so I can tuck it under my desk. It’s comfortable for a full workday, though the seat could be a bit softer. Overall, solid value for the price.
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Reviewed in the United States on May 2, 2026
★★★★★ 5
Comfortable and Good Quality
I'm happy with the chair and feels durable. It's supportive for my back and has good lumbar support. It was also easy to put together. Good value for the money.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 27, 2026
★★★★★ 5
Comfortable and easy to move around
This chair is really comfortable. The seat cushion is soft but supportive, and the mesh back keeps my back cool during long workdays. The lumbar support helps a lot with my posture. What I especially like is how smoothly the casters roll — glides effortlessly on my floor, no noise at all. Assembly was quick, around 10 minutes. The flip-up armrests also help save space when pushing the chair under my desk. Great value for the price. Highly recommend for anyone needing a solid, comfortable home office chair.
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Reviewed in the United States on June 7, 2026
★★★★★ 4
Great chair at a good price
It's a great chair, comfortable and reasonably priced for an ergonomic office chair. I usually don't write reviews, but I also understand how purchasing an office chair can feel overwhelming with so many choices.
I needed to replace the chair I'd purchased in 2020. At the time I'd not spent a lot of money, not sure if working remotely would be temporary or permanent. It lasted about as long as one might expect. I did quite a bit of research choosing a replacement. I'm always hesitant to purchase furniture without trying it out in person.
This chair is worth the price, not on the higher end of what's available but definitely not cheap. I've had it for about three weeks and so far, it's perfect for the 8-10 hours I spend in it during the week.
It arrived early, a great bonus. Assembly was quick, with easy-to-follow directions and all the tools and parts needed. (including some spare screws). I agree with others who mentioned that a spare set of hands would have helped, but I had no issue doing it myself.
It's a sturdy chair with good lumbar support. The adjustability of that feature can accommodate different heights. (I'm around 5'4") Changing seat height or whether the back tilts or remains stationary are all easy to accomplish. The one minor caveat is the seat is leather, so in warm weather and shorts season, it's not ideal. I solved that by purchasing a cover (because of the way the chair fits together, I purchased one that covers both the seat and back because a seat cover by itself would not work). That has worked fine and I'm not sure whether I'll keep the cover on all year.
Overall, it's a great chair at a good price.
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Reviewed in the United States on September 4, 2022
★★★★★ 5
Great office chair highly recommended!
This office chair is easy to assemble and the instructions are clear to follow. I am very impressed with this office chair, the seat is extremely comfortable after I sat for a long time and I feel relaxed.
Also, the lumbar can be adjusted and has great back support. Great price for the quality. Highly recommend those who are looking for the office chair.
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Reviewed in the United States on April 5, 2026
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