Corrosion, mechanical damage and wear are the most frequent causes of an exhaust system failure. Placed under the car, nearly all of the system components are exposed to corrosion: the damper, the catalyst, the silencers, the exhaust pipes and the hangers. Fortunately, you don't always have to replace the entire system. If the damages are not vast, it may be enough to just seal the system, weld it or replace only a part of it. If you use high quality parts, the system will remain tight for a few years to come. If, however, you apply cheap substitutes, the system will most likely fail again several months after the repair.