When the new MINI was introduced in 2002, there were two different flavors available for consumption, the regular Cooper and the Cooper S. The S version was a high-performance version of the standard MINI and, as such, featured a bevy of improvements, including suspension upgrades, larger wheels and tires, subtly different bodywork, and, perhaps most importantly, a supercharger that made the S quite a bit quicker than the standard MINI Cooper.
Upgrade the exterior to Cooper S specs. The S features chrome side louvers, which can be installed. The Cooper S also features a twin exhaust tip at the rear of the car, which can be bolted on. To provide air to the supercharger hiding under the hood, the Cooper S also has a large hood scoop in its hood. This will require that an entirely new hood be installed.
Install a supercharger. By far the biggest difference between the S and the regular version is the supercharger that the S features and that is responsible for most of its improved performance. The motor is the same 1.6 liter, but the supercharger forces more air into the motor, thereby increasing horsepower and torque. The S also features an intercooler to provide cold air to the engine and the supercharger. Installation of the supercharger and intercooler should be done by a certified MINI technician.
Install the S suspension. The Cooper S features heavier springs for increased road holding. It also features front and rear anti-roll bars to combat body roll, whereas the standard Cooper features only a front anti-roll bar. All of these parts are straight bolt-ons and are relatively easy to install with the proper suspension tools.
Replace the standard wheels with the Cooper S larger wheels and tires. The S featured larger-diameter wheels and slightly wider tires (175/65R15 vs 195/55R15) for increased grip and better handling. Cooper S wheels and tires are easy to install on a standard Cooper. Simply raise the car with a floor jack and swap the wheels for an instant visual and performance upgrade.