So I've been hearing a fluttering type sound going on that I origionally thought was just a leak. I plugged what leaks I did find, I even got some muffler mud and flat-out sealed the flange from the Cat back. (there are no other flanges beyond that).
I still hear the fluttering and Its coming from the catalytic area. the only thing i havent done is pull the shroud around the cat off and visually *look* but was curious if this may sound like a bad cat or not... It kinda seems like there is a lack of power at times. My average mpg is 23 city and about 26-27ish highway.
the fluttering kinda gets softer/quieter the hotter of a day it is and when i've been driving a bit.