right guys decided to post to see if I can get any ideas here. my exhaust has made a tinny buzzing noise ever since I bought the car. Arnold clark told me they all sound like that but I didn't buy it. seems to make the noise just over tickover when I rev it, can actually hold the revs there and the buzz goes constant. now ive put a decat (2nd cat) on it.....didn't cure it. now ive fitted a ktec cat back system aswell and hey.....didn't cure it. still there just as bad as ever. since fitting the ktec ive noticed when it buzzes it actually changes the exhaust note aswell now. so basically can only be either the first cat? or the manifold? any ideas will be much appreciated coz its doin my head in and it makes the exhaust sound absolute ****!