2003 Mustang GT - Strange thud noise under hood
This thud noise is very inconsistent. It does not matter what speed I'm going, what gear I'm in, or how long the car has been running - I didn't hear the noise for about a month but it just started back up again - it comes and goes and is not necessarily heard every time I drive.
I left the car running, put the car in nuetral, and popped the hood during the time the noises were heard to see if I could at least figure out what area it was coming from. It was coming from a black cylinder located in very back corner of passanger side and it has pipes coming out of it. When the noise happens, this part shakes.
I can only descride it as a thud noise really - it is rather loud. I was wondering if anyone knows what that part is, or what the problem could be?