| Manufacturer | Weistec |
| Street legal in all the US States | No |
| Transmission Family | GS7D36SG |
| Tuning Method | Cypher Pro Dealer |
| Needs Unlock? | No |
| Module Type | TCU |
| year | make | model | trim | engine |
|---|---|---|---|---|
| 2023 | BMW | M4 CSL | Base 8AT (G82) | Twin Turbo 3L I6 (S58) |
| 2025 | BMW | M8 Competition | 8AT (F91/F92/F93) | Twin Turbo 4.4L V8 (S63) |
| 2025 | BMW | M8 | 8AT (F91/F92/F93) | Twin Turbo 4.4L V8 (S63) |
| 2026 | BMW | M4 Competition | Convertible 8AT (G83) | Twin Turbo 3L I6 (S58) |
| 2025 | BMW | M4 Competition | Convertible 8AT (G83) | Twin Turbo 3L I6 (S58) |
| 2026 | BMW | M4 Competition | Base 8AT (G82) | Twin Turbo 3L I6 (S58) |
| See more | ||||
Product Description
BMW M badges its version of the ZF 8HP76 as M Steptronic, and it's the sole transmission offered on the current S58-powered M3, M4, M5, and M8, which says plenty about how much M trusts it. Like other ZF 8HP derivatives it's a torque-converter automatic rather than a dual-clutch, but its fast-acting solenoids and low-loss gearset let it go toe-to-toe with dual-clutch rivals on shift speed while still delivering the smoothness and launch behavior only a torque converter provides.
Weistec's TCU tune recalibrates that factory M Steptronic software, building directly on the 8HP76's own well-regarded engineering rather than working around it. Every factory safeguard, clutch-pressure limits, thermal protection, OEM diagnostics, remains active throughout, because this is done to the same calibration standard BMW itself applies, not some generic piggyback tune, an already outstanding gearbox, taken another level further.
How Do You Get Your BMW M Series TCU Tune Tuned?
Follow these steps — this is what your specific vehicle needs and supports.
Choose Your Tune Stage
Core Improvements
Standard with this tuneFree Add Ons
Pick Your Tuning Method

Cypher Plus
Order a Cypher Plus and tune your car yourself from your phone, entirely through the MyFlasher app. Watch how it works.

Mail It In
Remove your ECU or TCU and mail it to us for tuning. Required for some applications.

In Person
Bring your vehicle, or just your ECU/TCU, to our Anaheim, CA headquarters. Call 714-202-0005 or email sales@weistec.com to schedule.

Cypher Pro Dealer
Visit a certified Cypher Pro Dealer near you. Find one with our dealer locator.
Complete The Upgrade
An ECU tune alone won't remove all factory limits or fix how power reaches the ground. Add these to round out the upgrade with no limitations.
Read the full CPC & TCU breakdown →
What is a CPC module?
The CPC (Central Powertrain Control) is a separate control unit that manages things like the active exhaust valves, radiator fan, intercooler pumps, and speed limiter. On many newer Mercedes-Benz vehicles, it also houses torque limiters that can hold back an ECU tune from reaching its full potential.
What is a TCU tune?
A TCU (transmission control unit) tune delivers faster, firmer shifts with higher line pressure, reducing clutch slip and increasing the transmission's torque capacity. It's a worthwhile upgrade on its own, or paired with an ECU tune for a fully sorted powertrain.
Good to Know
- This is a reflash of your original module, not a stand-alone unit.
- Power gains vary by vehicle, modifications, fuel, and operating conditions (ambient temperature, altitude, etc.).
- New or upgraded spark plugs are always recommended when tuning.
- Product may not be emissions compliant. Check local laws prior to installation.
- Always use a battery charger during programming.
Fitment not confirmed
This part is not confirmed to fit your selected vehicle.

