Holley 550-1029 EFI Terminator X Max Stealth 4150 - GM LS Engines
SKU: 75905761799

Holley 550-1029 EFI Terminator X Max Stealth 4150 - GM LS Engines

Sale price$1326.15 Regular price$1473.50
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Description

Holley 550-1029 EFI Terminator X Max Stealth 4150 - GM LS EnginesBlack 24X Crank Trans Control 3. 5 in. Touchscreen Part Number: 550 1029 The Terminator X Stealth 4150 system features (4) 100 lb. hr. fuel injectors capable of supporting up to 650 HP naturally aspirated or 600 HP on forced induction applications. Taking the Stealth name, all of the wiring exits below the rear fuel injector cover for a clean installation. The timed spark port for vacuum advanced distributors is located under the front fuel bowl,

Black - 24X Crank - Trans Control - 3.5 in. Touchscreen

Part Number: 550-1029

The Terminator X Stealth 4150 system features (4) 100 lb./hr. fuel injectors capable of supporting up to 650 HP naturally aspirated or 600 HP on forced induction applications. Taking the Stealth name, all of the wiring exits below the rear fuel injector cover for a clean installation. The timed spark port for vacuum advanced distributors is located under the front fuel bowl, giving greater access to the distributor. Air entry is machined to fit most stock air cleaners with air cleaner locator provisions. The ECU features fuel maps that self-learn and integrated ignition timing control, yielding improved idle stability, drivability, and horsepower at wide-open throttle (WOT). The Stealth 4150 also includes transmission kick down provisions for GM TH350/400, 200R4/700R4, and Ford C4/C6 applications for making installation more convenient. These kits provide plug and play transmission control for GM 4L60 and 4L80 transmissions.

Features and Benefits

• (4) 100 lb./hr. fuel injectors supporting up to 650 HP naturally aspirated or 600 HP on forced induction applications
• 3.5” LCD handheld touchscreen for setup, tuning, gauge displays, and other viewing parameters
• Initial handheld calibration wizard creates a base tune with no laptop needed
• Advanced annular discharge rings for more fuel flow and better fuel atomization, nearly elimating the fuel delay issues found on other designs
• Bosch LSU 4.9 Wideband Oxygen (O2) Sensor for maximum performance on real time fuel map learning
• OEM style TPS/IAC robust design for longevity
• Internal 1 Bar MAP sensor built into the ECU
• Bolt on 4150 flange carburetor replacement fits many factory intake manifolds
• Air entry is machined to fit many stock style air cleaners with air cleaner locator provisions
• Plug and play transmission control for GM transmissions
• Integrated ignition timing control improves idle stability, fuel economy, and wide open throttle (WOT)
• All wiring exits below the rear fuel injector cover for a stealth installation
• For 24x or 58x GM LS engines
• Four inputs include 12V, ground, 5V, and frequency, for pressure sensors, activation triggers, trans brake, etc.
• Fuel and Oil Pressure inputs are pre-terminated
• Four outputs include ground, PWN-, for fans, boost and nitrous control, IAC, etc.
• Requires an external fuel pressure regulator with base pressure set to 58.5 PSI (Holley P/N 12-886 or equivalent)

Not recommended for 4x4 applications with electronic transfer cases, not compatible with 4L6X transmissions from model year 1995 or prior due to year-by-year changes in converter lockup and downshift strategy. ECU is not recommended for marine applications, but can be used on off-road applications as long as you choose a safe location, keep it dry, protect from heat, and ensure proper wiring management. Please refer to your owners manual for further installation instructions. Requires an external fuel pressure regulator with base pressure set to 58.5 PSI (Holley P/N 12-886 or equivalent).
Shipping Notes
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Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
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SKU: 75905761799

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C
Verified Purchase
Carb was beautiful once I got it tune in, cranks great runs smooth I would buy it again if needed
Draper, US
★★★★★ 5
For motorcycles
Size: 32 oz, Style: 32 Fl Oz, Pattern Name: Lube
Great stuff, good price
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 25, 2026
J
Verified Purchase
JNL
Massapequa, US
★★★★★ 5
The best lower unit gear oil I have used
Size: 32 oz, Style: 32 Fl Oz, Pattern Name: Lube
I have been boating my whole life, this is by far the best gear oil. I use this in my Johnson 115 even though this is technically made by Mercury. I seem to get less if any water intrusion into my gearcase with this oil. If there is any, the oil emulsifies the water and continues to protect the gears. I have had better luck with this than Pennzoil marine or others. Highly recommend. It is a blue color and easy to drain and fill.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on March 23, 2026
D
Verified Purchase
Debra
Charlottesville, US
★★★★★ 5
Great
Size: 32 oz, Style: 32 Fl Oz, Pattern Name: Lube
Great lube for the boat
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 19, 2026
J
Verified Purchase
Joshua Murray
Bozeman, US
★★★★★ 5
recommend
Size: 32 oz, Style: 32 Fl Oz, Pattern Name: Lube
great price
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 22, 2026
C
Verified Purchase
Christopher C.
Lexington, US
★★★★★ 4
Does not come with a pump.
Size: 32 oz, Style: 32 Fl Oz, Pattern Name: Lube
The Good: Changing the fluid in the lower unit is a very easy DIY job. This can save you hundreds of dollars each year by doing it yourself. The Bad: You need a special pump to change the oil, and sometimes it comes with the gear lube. Unfortunately this product did not come with it. Luckily my neighbor had an extra one from changing the lube a different boat laying around and was able to use that. The Ugly: If you have to go get the pump, that could cost a few extra dollar but is just an extra nuisance. The pumps are interchangable but you just need to clean it between uses (DON'T MIX DIFFERENT OIL BRANDS)
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on October 28, 2025

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