I just recently put a Magnaflow exhaust on my truck and I noticed the stock exhaust had some type of Anti Vibration device (I think) attached half way between the Cat (Y-pipe actually) and the Muffler.

My questions would be...
Is it an anti-vibration device? If not... what is it?
Did anyone else put it back onto their new exhaust system?

 

Its an exhaust dampner/anti vibration piece. If your new exhaust doesn't vibrate or rattle you don't need to worry about it.

 

I and my dealer have no idea what it is. The hanger on mine rusted and the thing was making a terrible noise ... Thought my front end was gone. Anyway we pulled it off and the problem went away... But it bothers me that a part that big is now gone and nobody seems to know what it is really for. Delaers advice... Dont worry about it ive never seen ti before.

 

Yes it's an anti vibration since the factory muffler is so heavy