In such cases the interior is stripped, and the required weight is achieved by adding ballast that allows precise control over weight distribution.
Along with weight requirements, safety requirements are present . Roll cages, fire extinguishers, reinforced bucket seats, seat harnesses, and the like are some of the required safety modifications.
In the late 1980s and early 1990s, grey import vehicles of Japanese performance cars, such as the Nissan Skyline, began to be privately imported into Western Europe and North America.
In the United States, this was in direct contrast to the domestic car production around the same time, where there was a very small performance aftermarket for domestic compact and economy cars; the focus was instead on sporty cars such as the Ford Mustang and Chevrolet Corvette, or on classic muscle cars.
Mapping can either be performed by changing the software within the ECU (chip tuning via firmware modification), or by providing false data via plug-in hardware.
Mechanical components can also be replaced, such as turbochargers or superchargers.
Engine tuning is the process of modifying the operating characteristics of an engine.