[VIDEO] HP Tuners Has Unlocked the C8’s Transmission Control Module for Tuning

Jul 7, 2026

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[VIDEO] HP Tuners Has Unlocked the C8's Transmission Control Module for Tuning

Back in February, HP Tuners announced that they have unlocked the E68 Engine Control Modules (ECM) of the C8 Corvette Z06 and ZR1 for performance tuning. This momentous achievement came several years after HP Tuners was able to crack the E99 EMC for the C8 Corvette Stingrays.

Right away, we started seeing performance car tuners jump in with both feet as they were now able to edit many of the engine’s parameters for more power. One the first ZR1s tuned was owned by Cleetus McFarland (aka Garrett Mitchell) and the dyno results showed the power increased to 1180hp/1094tq with a tune and downpipes while also running on MS109 race fuel.

Even though tuners were able to make more power with the addition of turbos or superchargers, there still remained an issue of clutch slip between gears, especially on Stingrays with forced induction. Unfortunately, tuners were still locked out of the Transmission Control Modules (TCM) to make those updates.

Until now.

HP Tuners teased us with big news happening today and then revealed that they have cracked the C8 Corvette’s T46 Transmission Control Module (TCM). Now, tuners can now fine-tune both the engine and transmission control modules for more power and controlling when the transmission shifts as well as adjusting the clutch/shift pressures and torque limits on the C8’s Tremec 8-speed dual clutch transmission.

The T46 TCM updates are available for nearly all C8 platforms from the 2020 Stingray through the ZR1. The Grand Sport and Grand Sport X aren’t yet supported but that’s only because they are just now shipping and will need to be tested first.

One of the companies working close with HP Tuners is Paragon Performance. In this reveal video, they are showcasing four HP Tuners-unlocked test cars that included a ZR1, a ProCharged E-Ray, and their shop’s Z06. Their resident tuning expert Graham tells us they have been working behind the scenes with HP Tuners in the lead-up to today’s announcement and are now offering a T46 TCM Upgrade Package.

“We’re adding a lot of forced induction setups to these Stingrays as people get them out of warranty and buy them secondhand. And one of the things that we always run into is clutch slip or shifting performance. We can handle it pretty well with the tuning that we do on the ECM side, but we’ve always kind of run up against a TCM limit. And now I’m really excited to be able to get around that and show you guys firsthand what that looks like.” – Graham/Paragon Performance

Graham talks us through some of the technical details but then takes the car out on the road. On one of these unlocked test cars, the stock/base tune showed visible clutch slip in 2-3 and 3-4 shifts. After flashing the custom TCM map to raise clutch pressures and revise the shift scheduling, the same shifts became “night and day” smoother. Graham reports even the tricky 4-5 shift, usually the hardest to clean up, came through crisp with no slip.

Check out the Paragon Performance video below with Korey and Graham as they show real-world testing and tuning with the T46 Transmission Control Modules: