In the automotive industry, the term performance parts is used for a variety of car and truck parts or accessories, that are designed to enhance a vehicles performance. The term is generally tied to the aftermarket industry which makes sense considering that car or truck enhancement parts or accessories are typically purchased after the original purchase. This is not to say that O.E.M. manufacturers wont create performance parts, because they often do.
Products such as Borla Exhausts, K&N Air Intake filters, ReadyLift Suspension Kits, or Bilstein shocks are considered performance parts because they are created to enhance car or truck performance. On the other hand, the O.E.M. exhaust, intake filter, suspension kit, or shocks that come with the newly purchased vehicles are generally stock parts designed to meet standards at a reasonable price. Someone looking to boost their car or trucks performance will then purchase an aftermarket part designed to boost performance.
Strictly being aftermarket however, does not categorize a car or truck part or accessory as a performance part. Aftermarket products may include seat covers, car covers, bumpers, sun visors,...