Noisy Exhaust

[Ralph219]

I live in Clacton and drive a late 1999, manual, 1.6 16v petrol Megane Scenic Sport. The car has just under 125k on the clock. The car is making a loud exhaust blowing type noise, so I took it to ATS, where they checked the exhaust through and said it was not blowing, but it needed a new cat which would cost me about £300. Now I’m a great believer in second opinions, so I took it to my neighbour who is a mechanic with a well equipped home workshop. He agrees that the exhaust is not blowing but disagreed with the need for a cat, he said the noise was coming from higher up. To cut a long story short, he changed the manifold gasket, which did show signs of blowing, and… the noise is still there. Between the manifold and the cat is a globe shaped item, He doesn’t know what it is, or what it does, or if it is needed but he is sure that the noise is coming from there. Does anyone know the purpose of this item, installed between the manifold and the cat? Help!!!