vibration of exhaust

[deano]

hi chaps
i own a mk3 golf gti 16v and most of the time when i am driving at just over 2000 revs a vibration noise comes from underneith the car. the heat sheild on the cat looks ok and so does the exhaust . can you help as it is starting to annoy me ?  

[richandhazel]

Its not the honeycomb within the cat itself is it? I had that with my Audi, the honey comb started to break up and rattled in the box.