ECU Remapping
Why Remap Power Figures Vary
By STX Tuning · 21 October 2026
The short answer
Remap figures are estimates. Engine condition, fuel, temperature, measuring method, factory tolerance and software differences all affect the number your car produces.
Engine condition
Worn spark plugs, a tired coil pack, a boost leak or a clogged filter can all reduce output, before or after tuning.
Fuel
Higher octane petrol can support more ignition advance on many engines. Results on 95 octane may be lower than on 98 or 99.
Temperature and conditions
Hot, humid air is less dense. The same car can measure differently on a summer afternoon and a cold morning.
Measuring methods
Rolling roads differ. Some read wheel power, some estimate engine power, and correction factors vary. Compare figures from the same rolling road only.
Factory tolerance
Engines leave the factory with slight variation. Some produce a little more than the brochure figure, some a little less.
Software differences
Different factory software versions and markets can change the starting point.
That is why we show estimates and never guarantee a figure. See performance gains or search your car.
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