Squeek coming from under the vehicle

my friend has a volkswagon golf 1996 and when the car is up to operating temp and you are stopped at a light soemthing underneath it sqeaks. We had it up on a lift and it sounds like it is coming from the exhaust, around the cat....could it possibly be the cat is gettin plugged? Any suggestions would be greatly appreciated:)

its normally the heat shields on the exhaust manifold or the cat.

yeah, i checked them when i had it on the lift and i couldnt seem to get it to stop by holding pressure on the heat sheild or anything...im gonna have it back up in a few days so i will check it again, thanks for the help:)