Considering an ECU remap for your GMC Sierra 6.6 Duramax 365hp? A Stage 1 remap can take this 1999 - 2007 diesel engine from 365 BHP to 395 BHP and from 894 Nm to 945 Nm of torque (turbocharged). This engine scores 5.5/10 for remap suitability. Get a free personalised quote from a trusted remap professional and find out exactly what your GMC Sierra can achieve.
The GMC Sierra 6.6 Duramax 365hp is a 6.6L turbocharged diesel engine producing 365 BHP and 894 Nm from the factory. With a typical Stage 1 remap, output increases to approximately 395 BHP and 945 Nm — a gain of around 30 BHP (8%) and 51 Nm (6%).
This engine has moderate remap suitability, though the available headroom is limited, so gains are modest compared to higher-output variants. The tuning headroom is classified as limited, based on the percentage gain available from the factory output.
Considerations: High tuned torque: check transmission torque capacity and service history.. Older diesel: injector, turbo and intake condition can affect results; ensure maintenance is up to date.
All figures shown are typical estimates based on aggregated Stage 1 data for this engine variant. Actual results depend on vehicle condition, mileage, and the chosen tuning method. We recommend discussing your specific vehicle with a qualified remap professional.
| Engine | BHP | Gain | Torque | Gain | Score |
|---|---|---|---|---|---|
| 4.3 V6 200hp | 200 → 220 | +20 | 350 → 370 | +20 | Moderate (4/10) |
| 4.8 V8 295hp | 295 → 315 | +20 | 414 → 435 | +21 | Limited (3.5/10) |
| 5.3 V8 295hp | 295 → 315 | +20 | 447 → 470 | +23 | Limited (3.5/10) |
| 8,1 V8 330hp | 330 → 350 | +20 | 610 → 630 | +20 | Limited (3/10) |
| 6.0 V8 360hp | 360 → 380 | +20 | 525 → 545 | +20 | Limited (3/10) |
Get a personalised remap quote for your GMC Sierra. We'll connect you with a trusted professional in your area.
All figures shown are typical estimates based on aggregated Stage 1 data for this engine variant. Actual results depend on vehicle condition, mileage, and the chosen tuning method.
We recommend discussing your specific vehicle with a qualified remap professional before proceeding.
