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MS3Pro Ultimate by AMP EFI for GM LS Engines, MS3Pro ULTIMATE GM LS 24x, MS3Pro ULTIMATE GM LS 58x
MS3Pro Ultimate by AMP EFI for GM LS Engines, MS3Pro ULTIMATE GM LS 24x, MS3Pro ULTIMATE GM LS 58x
MS3Pro Ultimate ECU by AMP EFI
MS3Pro ULTIMATE with GM LS 58x Plug and Play Harness
AMP EFI MS3Pro Ultimate Black Center Harness Flying Lead
Serial Cable

MS3Pro ULTIMATE with GM LS 24x Plug and Play Harness

From: $2,099.99

Product Quantity

GM LS 24x Injector Style ULTIMATE


Alternator Lead Extension


Seals-It Grommet - 1.00" split


AMP EFI CAN Trans Control Module with 4L60E Subharness


AMP EFI CAN Trans Control Module with 4L80E Subharness



MS3Pro ULTIMATE GM LS 24x Plug and Play includes an MS3Pro ULTIMATE ECU, TunerStudio software and the most rugged & durable GM 24X custom harness available. 

Experience the MS3Pro ULTIMATE.

The Ultimate brings NEXT LEVEL capability to MS3Pro’s staggering feature set beginning with a new high quality aluminum IP65 rated, water resistant enclosure.  The MS3Pro ULTIMATE provides 10 programmable peak and hold injector channels for driving any saturated or peak and hold injectors as well as loads of additional I/O eliminating the need for any other controllers, saving you unneeded complexity and weight.  Out of the box ready for naturally aspirated and boosted applications with on-board 4-bar MAP and barometric pressure sensors, MS3Pro ULTIMATE was designed to handle your engine combo without breaking a sweat!

No need for a separate data acquisition system, the MS3Pro ULTIMATE will log up to 64 channels, conservatively, at 200hz. The advanced TunerStudio software provides an intuitive, straight-forward tuning experience for pros and enthusiasts alike with best in class self-learning, self-tuning fuel table strategies to assist you.

Visit MS3Pro ULTIMATE product page for a complete features listExperience for yourself why more and more racers and performance enthusiasts are recognizing and choosing MS3Pro over the competition.

The MS3Pro ULTIMATE GM LS 24x Plug and Play Harness is the highest quality, best value option for LS Motors in the industry today.  Save your hard earned time and money while experiencing the virtually limitless feature set of MS3Pro ULTIMATE Engine Management System.  Simply choose your injector style from the drop down menu!

Professionally engineered and easy to install,  fire up your engine on day one!   All wiring is composed of TechFlex woven, self-extinguishing wrapped hi-temp TXL & GXL automotive grade wire with OEM Delphi & TE connectors. Reach the battery under the hood or in the trunk with 4 gauge power & 10 gauge ground wires.  All relays and fusing live in a single, waterproof fusebox and the fuel pump wiring / relays / fusing is big enough for pumps that can handle 1000whp or more right out of the box (10ga wire, 30amp circuit).  Additionally, all of the available I/O of the MS3Pro ULTIMATE are brought out in the harness to make expansion as easy as possible regardless of the featureset you’re planning to use, allowing for killer features like traction control, bump box, table switching, flex fuel, and more.  This harness was designed with room to grow!  And did we mention it’s show-quality-drop-dead-gorgeous?

This harness also is designed for optional automatic transmission control using the AMP EFI CAN transmission controller; Just plug in our transmission controller using the proper sub-harness (for 4L60E or 4L80E) and you’re ready to control your trans!

Required connections:
Constant Power
Constant Ground
Switched Power
Alternator light

Suggested extra connections:
Fuel Pump Power
Tachometer Signal

The MS3Pro ULTIMATE GM LS 24x Plug and Play Harness is configured for a cable operated throttle body. The included connectors are set up for an LS1 style throttle position sensor and IAC valve. Four barrel style or independent throttle body setups may require modifications to the harness.

Note that the alternator connection is designed for high mount alternators such as Corvette and truck setups. Low mount alternator setups, as well as other aftermarket accessory drives that do not have the alternator high on the driver’s side, require our alternator extension cable.

MS3Pro ULTIMATE GM LS 58x Plug and Play

*All parts are sold for OFF ROAD RACE-ONLY, ground-vehicle use only. Aftermarket EFI/EMS systems are not for sale or use on pollution controlled vehicles. Alteration of emission related components constitutes tampering under the US EPA guidelines and can lead to substantial fines and penalties. Your state/district may also have specific rules restricting your tampering with your vehicle’s emissions system. In short, as stated before, our official policy has to be RACE or OFFROAD USE-ONLY in ground based vehicles ONLY.

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Drivers for the USB connection can be found on the FTDI website

The latest MS3Pro firmware & tuning software can always be accessed at

MS3Pro ECU Feature Comparison: 1st Gen – EVO – ULTIMATE

What is in the box?

    • MS3Pro ULTIMATE Standalone EFI Controller
    • LSx drop on wiring harness for LS motors with a 24x crank trigger
    • Fuse block with relays
    • USB and serial communications cables
    • Matching connectors for O2 and transmission / CAN subharness
    • Fuel pump ground wire
    • Includes TunerStudio registration code
    • USB drive (for software / documentation / base maps)

How big is the ECU?

    • The MS3-Pro measures approximately 8.5″ long (including the mounting ears), 4″ wide, and 2″ tall including the mating connectors.

Where is this product manufactured?

    • The ECU is manufactured in Gainesville, Georgia, USA. The wiring harness is also American-made.

What is the warranty on the MS3-Pro?

    • It carries a one year warranty against manufacturing defects.

How watertight is the box?

    • The case uses an o-ring seal and sealed connectors to ensure it is completely splashproof, and will keep water out if completely immersed up to a few inches for a few  minutes (which normally shouldn’t happen, right?).  If you need further water submersion resistance that can be accomplished with a small bead of silicone just inside/outside of the o-ring.

Will I need to modify the harness to fit the mods on my engine?

    • This harness works with car, truck, and most aftermarket intakes that use a forward facing throttle body. Intakes that use a center mounted throttle body, independent throttle bodies, or reverse mounted intakes (with the throttle facing the bellhousing) will require minor modification.
    • The alternator connection is set up for an alternator mounted high on the driver’s side, like the truck or Corvette accessory brackets. Setups that mount the alternator low (Camaro, Firebird, GTO, and CTS-V, for example, as well as many aftermarket setups) will need an extension. Our alternator extension harness provides a good way to add this.
    • We anticipate most customers won’t be using the factory O2 sensors. We have brought these out to an Amphenol AT connector for making your own O2 harness.

What size screws do I need for the fuse box mounting?

  • It uses #10-32 mounting screws.

Does this harness have the MS3-Pro controlling the alternator?

  • No. You will need to wire the alternator to the charge lamp. That will activate the alternator. See details in the manual.

What sort of throttle body do I need?

  • You will need to run a cable operated throttle body. The connectors included will plug into an LS1 style throttle position sensor and IAC valve.

Can I run big low impedance fuel injectors with Ultimate?

Questions & Answers

    I'm doing a miata v8 swap with a 5.3L, is the compatible to plug and play for the engine side?
  1. 0 votes
    Q I'm doing a miata v8 swap with a 5.3L, is the compatible to plug and play for the engine side?
    Asked by Trevor

    Yes - it just needs to get power, ground, and a few other connections from the original Miata wiring. Contact our tech support department if you have any questions.

  2. I'm looking to use this on my 2000 Chevrolet Silverado 1500 5.3/4L60E. The truck previously had a v6 in it. Will I need anything else to get my truck driving outside of this setup?
  3. 0 votes
    Q I'm looking to use this on my 2000 Chevrolet Silverado 1500 5.3/4L60E. The truck previously had a...... Read more
    Asked by Nick Swanson

    If you get the 4L60E control package for this installation, this is a pretty complete package - tunable racing ECU, wiring, everything. If you are tuning it yourself or if this is a turbo build, we also recommend adding a wideband O2 sensor like an Innovate LC2; this makes the tuning process a lot easier.

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