Factory detuned D250 and D300 calibration features restrained throttle mapping, lower boost thresholds and reduced torque output. For instance, stock tuning creates sluggish low-speed response, limited overtaking power and weaker towing capability. In addition, many owners purchase higher-spec hardware-equipped models locked behind factory software restrictions. Meanwhile, generic aftermarket diesel remaps often exceed JLR safe thermal limits, which commonly cause overheating issues, DTC fault codes and shortened engine lifespan.