A cat-back exhaust system is an aftermarket modification for vehicles that replaces the exhaust components from the catalytic converter to the rear of the vehicle. This system typically includes the exhaust pipe, muffler, and tailpipe, enhancing the vehicle's performance and sound. Installing a cat-back exhaust can improve exhaust flow, which may lead to increased horsepower and torque. Additionally, it often provides a sportier sound compared to the factory exhaust, appealing to car enthusiasts looking for a more aggressive tone while driving.