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Description
Holley Terminator X MAX Engine Management Systems 550-926TERMINATOR X MAX MPFI W TRANS & DBW, LS1 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 & DBW, LS1
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 550-926 also has 4L60E or 4L80E Transmission control and Drive-By Wire Throttle Body 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 LS1/LS6 engines with 24x crank reluctor with EV1 injectors and 4L60E/4L80E transmissions, and drive-by wire throttle body control.
- 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 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
- 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
- Recommended Pedal part number - 10379038
- Includes: 24x LS Engine Main Harness - EV1 Injector Harness - DBW Throttle Body 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
Specs
| Brand | Holley EFI |
|---|---|
| Crank Reluctor | 24x |
| Emission Code | 3 |
| Ignition Type | GM LS 24x |
| Injector Connector | Jetronic / Minitimer (Bosch) |
| Product Type | Terminator X Max LS MPFI |
| Terminator LS Options | Fuel, Spark, Drive-by-Wire, Transmission |
| Part Number | 550-926 |
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
4.1 ★★★★★
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Product Reviews
★★★★★ 5
Great upgrade for a rental apartment mattress
The mattress in my rental place is firm to the point where it almost feels unfinished. Instead of replacing it, I decided to try adding this topper. It made an immediate difference in the way the bed feels when I sit or lie down. There’s a nice cushioned layer that softens that “flat” feeling but still holds its shape. Another thing I noticed is how breathable it is. I expected thick padding to feel warm, but the airflow here feels better than the original mattress surface. Even after moving around, it never felt heavy or stuffy.
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Reviewed in the United States on November 22, 2025
★★★★★ 5
Soft and Comfortable Topper
I got this bamboo mattress topper for a small single bed we keep in our guest room, but I ended up testing it out myself first. The material feels soft and breathable, which is nice because that room can get a little warm in the afternoons. It adds a good amount of cushioning without making the bed too soft. After a couple of nights, my back actually felt better compared to the old mattress alone. I also appreciate that it’s machine washable, because our guest room sometimes doubles as a nap spot for my son after swim class, and spills happen. It dried pretty quickly in the dryer and kept its shape. Overall, it made the bed feel much more comfortable and fresh.
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Reviewed in the United States on November 24, 2025
★★★★★ 5
Added comfort for someone working night shifts
I work odd hours, so my sleep schedule is all over the place. My mattress has always felt a bit too stiff after long shifts, so I got this topper hoping it would help me relax faster. It really changed the overall feel of the bed. The padding has a cushioned lift that makes lying down feel smoother, especially around the shoulders and lower back. Instead of feeling like I’m dropping onto a firm surface, there’s a soft layer that evens out the pressure. What surprised me most is how light the surface feels. Even after staying in one position, it never gets stuffy or heavy. The airflow makes a difference when your body is trying to wind down after work. The fitted pocket also stays tight around the mattress, so nothing shifts when I move. I can stretch out without worrying about the topper sliding off.
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Reviewed in the United States on November 24, 2025
★★★★★ 5
Good option for softening a college apartment bed
I moved into a college apartment where the bed felt like it belonged in a dorm from years ago—flat and stiff. Instead of dealing with it, I tried this topper, and it added a cushiony layer right away. The surface feels much more forgiving when I fall onto the bed after studying or hanging out with friends. It has just enough padding to take away that board-like feeling without making the bed sag. Another thing I noticed is how breathable it is. I expected something this thick to feel warm, but it actually stays cool even if I stay on one side for a long stretch.
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Reviewed in the United States on November 19, 2025
★★★★★ 5
Makes an older family mattress feel brand new
There’s an older mattress in my place that everyone avoids because it feels too worn in the middle. Instead of replacing it, I decided to give this topper a shot. Once it settled on the bed, it added a thick cushioned layer that helped level out the whole surface. Lying down feels smoother, and the middle no longer dips the way it used to. The fabric feels cool when you touch it, and it keeps that same feel even after staying on it for a while. I thought a thick topper might hold warmth, but this one keeps the air moving enough that the bed stays comfortable throughout the night.
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Reviewed in the United States on November 25, 2025