SKU: 75558121275

Holley Terminator X Engine Management Systems 550-909

Sale price$719.98 Regular price$799.98
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Ships within 48 hours · Estimated delivery Aug 5 - Aug 10

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Description

Holley Terminator X Engine Management Systems 550-909TERMINATOR X MPFI, LS1 W EV6 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.

TERMINATOR X MPFI, LS1 W/ EV6 

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. 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 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 EV6 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
  • 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 - EV6 Injector Harness - Terminator X ECU - ECU Main Power Harness - Bosch LSU 4.9 Wideband Oxygen Sensor - Input/Output Harness - and assorted vacuum adapters.

Specs

Brand Holley EFI
Crank Reluctor 24x
Emission Code 3
Ignition Type GM LS 24x
Injector Connector USCAR (EV6)
Product Type Terminator X LS MPFI
Terminator LS Options Fuel, Spark
Part Number 550-909
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. 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
SKU: 75558121275

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4.1 ★★★★★
Based on 9 reviews
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Verified Purchase
Amazon Customer
Phoenix, US
★★★★★ 5
Perfect Pillow
Size: Queen (Pack of 1), Color: White
These are the best pillows ever. You can adjust the firmness or softness to whatever you want. For years i used a soft latex pillow , which you cant get anymore. I will never use another pillow. I have purchased 6 of these after the first one. You pick your own comfort level. Best ever. No more neck aches.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 17, 2026
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Mark
Belleville, US
★★★★★ 5
Hallelujah… finally, I found the right pillow!!!
Size: Queen (Pack of 1), Color: White
I have spent a lot of money searching for the right pillow. I recently tried to Tempur-pedic that cost twice with this pillow cost. Tempur-pedic flattened out. I’ve had this pill for a few weeks now and it works wonders. I am a paraplegic. You can have a lot of neck problems. I love the fact that this pillow is adjustable. I immediately saw it was too stuffy and took a bunch out. It works perfect so glad I didn’t spend money on a $200 purple pillow. I read a lot of reviews and there were a lot of complaints about the odor. Mine did smell funny when it came out of the box. I immediately threw it in the dryer with a few bounce fabric sheets came out smelling fine. Pillows are a very individual thing, but I think for 40 bucks this pillow is worth a try. I’m really enjoying mine about one of those silk pillowcases to go over it and it sleeps cool and comfortable. Best wishes in your search for the right pillow. Update: I’ve been using this pillow several months and it continues. Give me a good night rest pain-free.. well worth the money. UPDATE: I have been using this pillow for three months and it still works great. It does not flat out or get hot..
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Reviewed in the United States on January 29, 2026
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Verified Purchase
Danica Mandic
West Palm Beach, US
★★★★★ 5
Soft comfortable very good pillow
Size: King (Pack of 1), Color: White
I really love my new pillow it's great and comfortable. Yes, it has a little smell, but if you wash the pillowcase and put the pillow on the window for a day you won't notice anything anymore.
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Reviewed in the United States on May 18, 2026
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Zachery Jeffries
Whiting, US
★★★★★ 5
Best place for head
Size: Queen (Pack of 1), Color: White
Do you love not getting sleep and sweating all over your pillow at night when you are asleep? If so then don't buy this pillow! If you want a good nights sleep and cool pillow like me this is the one. Ive always been ehh towards spending so much on a pillow but its 100% worth it, I sleep so much better and it forms to my head and keeps me cool at night. Great support even for my big head and comes with a bag of extra stuffing if you want to have a little more firmer pillow. Highly recommend
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Reviewed in the United States on April 4, 2026
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Loves_2_read
Waukegan, US
★★★★★ 3
Oversized
Size: Queen (Pack of 2), Color: White
I have chronic neck pain. I am forever buying new pillows. Sometimes I think I found the perfect pillow but then three months later they’re losing their loft. I thought I would give these pillows to try since the stuffing is removable. Now these pillows are really oversized. To the point where I thought that they had sent me king-size pillows but I double checked the packaging and they were Queen. I ended up having to buy king-size pillowcases for them because they just barely fit in the queen size and the pillowcases would always end up pulling back from the edge. So that’s a negative one star there. Now I’ve been sleeping on these pillows for a while and they have held up well. I did end up removing some of the stuffing because it was just too much. I’m a side sleeper and when I use this pillow, it does a good job of keeping my neck in alignment. However, the pillow tends to migrate up as I sleep. Or I tend to slip down off the pillow, either or. So that’s why I’ve removed a second star. Maybe if I removed more stuffing that wouldn’t happen, but then I feel like the loft would be too little. I will say that these provide great support when sitting up in bed reading or watching TV. So would I buy them again? Probably not. Am I going to keep using them? Yes
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on December 23, 2025

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