Most of the Volkswagen, Audi, Seat and Skoda exhaust systems fitted at the factory are well made, however, they have not been optimised when it comes to horsepower and torque.
A performance exhaust can free some of the power in your engine. Performance exhaust systems allow for a quicker, more efficient path for exhaust gases to escape. This means your engine "breathes" better, so spent fuel and air exit the combustion chambers faster and new fuel and air can be burned to create more power.
The way the pipes are bent also affects the exhaust flow and there are two types of bends used in making exhaust systems. The typical factory-made systems, as well as some aftermarket systems, use a "crush-bend" technique. This type of process creates a crinkled area in the pipes, decreasing the diameter and slowing exhaust gases. A mandrel bend is smooth and does not affect gas flow. The pipe is a constant diameter through the bend, yielding less resistance for a more efficient and better performing exhaust.