DIESEL R RTD4 Tune Files (2024-2025 Duramax L5P 6.6L) - Global B

The 2024–2025 L5P RTD4 Tune File that customers have been waiting for is now available. This is a single-level, +125HP custom tuning file created for the 2024-2025 6.6L Duramax L5P equipped with the latest E42 (Global B) ECM. It’s written for the HP Tuners RTD4 platform and designed to deliver clean power with no guesswork.

This RTD4 custom file is dyno-tested on real 2024–2025 L5P trucks. The stock output baseline was 433HP. With this file, our dyno pulled 575HP and 1,230 lb-ft of torque.  Speed limiter has been removed.. It’s calibrated for drivability, towing, and power under load — not just theoretical numbers. It’s a safe, no-nonsense first step into real E42 tuning.

To run this file, your ECM must be unlocked using the Dieselr E42 Upgrade Service. We require your VIN before purchase, and you’ll complete a tuning form after unlock.