2004.5 - 2005 GM 6.6L LLY Duramax | Allison Transmission Tuning by PPEI.
2004.5 - 2005 GM 6.6L LLY Duramax | Allison Transmission Tuning by PPEI.

2004.5 - 2005 GM 6.6L LLY Duramax | Allison Transmission Tuning by PPEI


Enhance your driving experience and extend the lifespan of your Allison transmission with PPEI’s Transmission Tuning, specifically designed for the 2004.5 - 2005 LLY Duramax. PPEI’s 5-Speed Allison transmission tuning is a game-changer for your LLY Duramax, whether you seek optimal performance or overall reliability.

Key Features:

  • Adaptive Shift Strategy: Tailored to improve the overall performance of your LLY Duramax’s Allison 5-speed transmission, our tuning adjusts shift points dynamically, ensuring a smoother and more responsive driving experience.
  • Refined Shift Points: Say goodbye to the low RPM "Lazy" feel. Our tuning eliminates the need for aggressive throttle inputs for downshifts, enhancing fuel efficiency and drivability, especially for trucks with larger tires and, most importantly, LLY Duramax trucks equipped with aftermarket turbos.
  • Turbo Lag Reduction: Experience reduced turbo lag with optimized upshifts and downshifts, keeping your engine in the ideal RPM range for maximum efficiency and power delivery.
  • Torque Converter Lock-Up Refinement: Our transmission calibration fine-tunes the torque converter lock-up strategy, delivering power to the ground more efficiently. This not only boosts fuel economy but also reduces heat build-up in typical unlocked conditions.
  • Customizable to Your Needs: At PPEI, we understand that every driver is unique. If you have specific requirements or preferences for your transmission calibration, our team is ready to customize it to fit your driving style.

Enhanced Durability and Economy:

PPEI’s Allison 5-Speed Transmission Tuning is not just about performance; it's about longevity and efficiency. Fine-tuning the transmission’s operation helps extend the life of your transmission and improves your fuel economy. PPEI’s Transmission tuning is an essential upgrade for the LLY Duramax trucks with additional horsepower and torque.

Whether you're driving around town or hauling heavy loads, PPEI's Transmission Tuning for the LLY Duramax is the best and only transmission tune that unlocks the full potential of your truck. At PPEI, transmission tuning is a must for all vehicles, whether tuned or not. A properly tuned transmission will not only make for an enjoyable driving experience but will also extend the life of your truck’s transmission while allowing your truck to perform at its optimal ability.

Installation Compatibility:

Installing the PPEI Transmission Tuning is straightforward with the right tools. It's compatible with the following EFILive Hardware:

  • EFILive AutoCal V2/V3
  • EFILive FlashScan V2/V3

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Customer Reviews

Based on 5 reviews
Sherwin Schmidt

Professional group of guys and amazing tunes. Looking forward to doing more business with them.


I made a review earlier about my trans tune(can’t figure out how to delete so making a new one). Logan contacted me after my review and helped me send him a data log so he could revise it. The shifts are way more accurate in terms of when it should actually shift. I no longer have to hammer the throttle for it to shift down when it should. Tc locks up a lot sooner when you get on it and pulls way harder. Great customer service. 10/10


I got this trans tuning being told and thinking it was gonna lock up in 2nd gear kinda like tow haul but it seems like the earliest it will lock is 4th and that’s if I’m really getting on it. Little bummed as my TC has a little higher stall than stock and I like the feel when it’s locked and puts power to the ground. Guess I can just keep using the button like I have been. Besides that the shift are a little quicker and more responsive it seems like so that’s nice. Price seems kinda high for what you get. Customer service is great, I got support even after hours. That’s really appreciated.

Garett Townsend
Allison trans rune

Good shifting and ordered to go along with my 60 HP tune on my 04.5 LLY

Pie Hanks
Very knowledgeable group of guys

Installed tune as instructed with no problem. Truck wasn’t performing correctly but after a few data logs and some trouble shooting they figured out the problem which was on my end. The cold air intake I had previously installed was not working properly with my setup. They gave me a few suggestions and to try and got it fixed. They were very helpful. Highly recommend them.


PPEI, also known as Power Performance Enterprises, Inc., is led by the business owner and lead calibrator/tuner Kory Willis. PPEI began calibrating/tuning back in 2008, specializing in Diesel Performance but has since expanded into the Gas and Powersports industries. Kory and the team at PPEI have set many world records along with continuing many industry “firsts”. We take pride in knowing that Kory not only prides his work, but also thoroughly enjoys setting expectations high for our team so our customers can have the best products available in the world.