All modern vehicles are controlled by an Electronic Control Unit (ECU) that monitors dozens of sensors hundreds of times per second, and responds to driver inputs in order to control the many different functions of an engine, including fuel injection, boost pressure, acceleration, and also emissions control systems such as Exhaust Gas Recircultion (EGR) and Diesel Particulate Filtration (DPF).

The electronic functions of an engine can therefore be modified for increased performance or economy through the use of external plugin modules, or by directly modifying the software found on the ECU itself, in a process known as tuning or remapping. The products found in this category are intended for use in conjunction with an ECU remap, or as a standalone performance addition. Some are intended for offroad/race use only.