In sports car racing, balance of performance (BoP) is a regulation and mechanism that maintains parity between competing vehicles by adjusting limits on a car's parameters, such as horsepower, weight, engine management, and aerodynamics to prevent a single manufacturer from becoming dominant in a racing class or series. History The origin of the term "balance of performance" dates back to the creation of Group GT3 in 2005 for the 2006 racing season, using experience learned from homologation special phenomenon in previous GT classes, although other series such as British Touring Car Championship and Japanese Super GT series had applied different concept in the past (and still in effect today) called success ballast, which only affected the weight of a competing car for each round in case of win or placement in previous events. (Deutsche Tourenwagen Masters also previously featured a success ballast system named as BoP between 2015 to 2017 until it was scrapped with two races left in the 2017 season). The aim of the system is to allow development of various racing models within a class, without leading to expensive development wars between manufacturers. The system was later adopted for other production-based racing classes such as Group GT4, LM GTE and TCR Touring Cars. Although one-make, open-wheel and prototype car racing typically do not use a BoP system, a similar system was devised for LMP1 class in FIA World Endurance Championship called equivalence of technology (abbreviated EoT), that allows for parity between hybrid and non-hybrid cars in the class. Additionally, DPi cars in the IMSA WeatherTech SportsCar Championship are subject to balance of performance as well. Mechanism Balance of performance is assigned by testing and analysis of a certain model's performance through previous races, although alternate methods may be used if the competing vehicle is new. For example, for GT3 cars, SRO holds two BoP tests a year at Circuit Paul Ricard, with cars driven by professional racing drivers who would have driven the car, to assess the performance of, and thus assign the BoP, of each car. These cars are equipped with an organizer-supplied telemetry device so that the organizer can gather data to allow the balancing of the cars, with new-to-class cars also subject to wind tunnel and dynometer testing. Once the results are obtained, various aspects of the car that can affect the car's performance such as engine horsepower, vehicle weight, aerodynamics, are then adjusted.