Problem started around October 2008. The rattle is not very loud but definitely from the cat. The thing is that this only happens in gear, and only when accelerating. If I am in neutral or park, I can rev all day with no trouble. Checked the thread but I am over 120000. Could it have something to do with the flexing of fuel line or something during those turns and hard acceleration. If I try to gun it from a stop going straight it does it too. Could that flexing cause me to loose a vacuum if there is a hairline crack? Thanks