Most exhausts have flexible section in them to allow the engine and exhaust to move independently of each other. A lot a manufacturers these days are putting the flex on the same section of exhaust as the cat. That means that when the flex goes you have to bin the cat and dig deep to replace the lot. At AA Silencers we can replace the flex by itself. We weld in a flex to the same specification as your original exhaust often for less than half the price of a replacement exhaust.