Holley EFI Terminator X Max at N2 Speed
Holley EFI Terminator X Max is a complete standalone engine management system for GM Gen III LS swaps. N2 Speed carries the 550-927 kit for 4.8, 5.3 and 6.0 truck engines with 24x crank and 1x cam sensors and drive-by-cable throttle. It replaces the factory PCM entirely with a self-tuning ECU, a 3.5 inch touchscreen handheld, and transmission control for the 4L60E and 4L80E, which is what makes it a practical answer for a swap chassis with no usable factory wiring.
Holley EFI Products We Stock
| Product | Part # | Price | Fitment / notes |
|---|---|---|---|
| Holley EFI Terminator X Max — Gen III 4.8/5.3/6.0 GM Truck Engines | HLY-550-927 | $2,199.95 | 24x crank / 1x cam, drive-by-cable, 4L60E & 4L80E control |
When to run standalone instead of tuning the factory PCM
If the engine is still in its original vehicle with a working factory harness, tuning the OEM PCM with HP Tuners is cheaper and keeps the factory features intact. Standalone makes sense when the engine has been swapped into another chassis, when the factory PCM and harness are gone or unusable, or when you need control the OEM computer will not give you. Terminator X Max covers the swap case: complete harness, its own ECU, and automatic transmission control.
What Terminator X Max includes
The kit ships with the ECU, a main engine harness, a 3.5 inch color touchscreen handheld, and the sensors required for the listed Gen III combination. It supports up to 8 injectors, self-tuning fuel strategy, and 4L60E/4L80E transmission control with adjustable shift points and line pressure.
Holley EFI FAQ
What engines does the 550-927 Terminator X Max fit?
GM Gen III LS truck engines — 4.8L, 5.3L and 6.0L — with 24x crankshaft and 1x camshaft sensors and a drive-by-cable throttle body. Confirm your reluctor and throttle type before ordering, since 58x Gen IV engines and drive-by-wire setups need a different part number.
Does Terminator X Max control an automatic transmission?
Yes. The Max version adds transmission control for the GM 4L60E and 4L80E, including shift points, shift firmness and torque converter lockup, all set from the handheld.
Is Terminator X Max self-tuning?
It has a self-tuning fuel strategy that adjusts the base fuel table from the included wideband feedback after a guided setup wizard. For maximum power or forced induction, a professional calibration is still the right move.
Do I still need a laptop?
No, basic setup and tuning run from the included 3.5 inch touchscreen handheld. Holley EFI software on a laptop is available if you want full table-level access and datalogging.
Can N2 Speed tune a Holley EFI system?
Our core tuning work is OEM ECU calibration for Dodge, RAM, Jeep, GM and Ford. For Holley standalone support, call (954) 406-8550 or email sales@n2speed.com and we will tell you what we can do for your build.
Should I swap to standalone or unlock my factory PCM?
If your factory ECM can be tuned, keep it. GM ECMs are not locked, so a factory GM PCM can be tuned directly with HP Tuners. Standalone is for swapped chassis, missing or damaged factory electronics, and heavily modified combinations.
Questions on fitment or tuning? Call (954) 406-8550 or email sales@n2speed.com. N2 Speed, 1461 SW 30th Ave Bay 16, Pompano Beach, FL 33069.