[V8] Exhaust re-installed, but now we have vibration at idle

[Scott Phillips]

I give you all a different possibility: 

They welded on the exhaust. They used the center support bearing bracket
as a ground the weld passed thru the bearing creating a scar on the
balls. 

OR:

A part of the new exhaust is touching the rear subframe somewhere
creating a resonance noise from the engine running. 

That'd be my guess. 

Scott P