6.6L L5P GM DURAMAX (2024-2026) ENGINE TUNING HP TUNERS RTD4/MPVI4

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2024–2026 L5P Custom Tune File – Now Available

*ECM UNLOCK AND HP TUNERS DEVICE NOT INCLUDED*

The 2024–2026 L5P HPTUNERS Tune File that everyone has been waiting for is finally here. This is our single-level, up to 200HP+ custom tuning file built specifically for the 2024–2026 6.6L Duramax L5P equipped with the latest E42 (Global B) ECM. It’s designed for the HP Tuners RTD4/MPVI4/MPVI3 platform and delivers clean, reliable power with zero guesswork.

This RTD4 calibration has been dyno-tested on real 2024–2026 L5P trucks. Factory output averaged around 433HP, and with this tune, we recorded 600+HP and 1,200+ lb-ft of torque. The speed limiter is removed, and the file is engineered for drivability, towing strength, throttle control, and power under load — not just inflated peak numbers. It’s a safe, straightforward entry into true E42 tuning.

To run this file, your ECM must first be unlocked using an E42 ECM Unlock Service. Your VIN is required before purchase, and a tuning form will be completed once the unlock is done.


Quick Overview:

  • Up to +180HP single-level tune for 2024–2026 L5P Duramax

  • Built for HP Tuners RTD4/MPVI4/MPVI3 (device sold separately)

  • Requires 8 HP Tuners credits to flash

  • E42 ECM unlock required (Global B platform)

  • No SOTF or multi-level power options

  • Speed limiter removed

  • CAN bus plugs not yet available — NOx & DEF modules must remain plugged in or tied into place; functionality is unaffected

  • Free updates included for single-file owners


This marks the official release of our first tuning support for the 2024–2026 L5P Duramax. If you're ready to unlock your E42-powered truck and finally tune it the right way, this is the file you need.

Order your 2024–2026 L5P Tune File today and experience real results.