Possibly a bad cat?
Could this be a clogged cat?
I have Pacesetter LTs with a custom y-pipe and 1 hi flow cat after the Y. Dont ask me why I did this. I realize it is pointless to have the cat so far back.
Its kinda like this
Headers--------
......................---y pipe----------hi flow cat---------loudmouth
Headers--------
As far as performance goes I have noticed a very slight drop in power. Not a great loss but its definately noticeable. And like I mentioned the exhaust seems to not be as loud.
So it turns out to be a clogged cat. On my way down to the shop I had to get on the highway. While I was on the onramp I hit about 4k RPMs and heard a *pop* and a bunch of **** fly out the back of the tailpipes. Since then it has been LOUD as *****. A-FRICKING-LOT louder than when the cat was first installed.
Anyhow its getting gutted as we speak. Thought Id update.
So it turns out to be a clogged cat. On my way down to the shop I had to get on the highway. While I was on the onramp I hit about 4k RPMs and heard a *pop* and a bunch of **** fly out the back of the tailpipes. Since then it has been LOUD as *****. A-FRICKING-LOT louder than when the cat was first installed.
Anyhow its getting gutted as we speak. Thought Id update.
That must have been funny. Sounds like you blew everything out of the cat already. When my passenger side cat when bad, it was making a horrible rattling sound, and if I gave it more than half throttle, the car just fell on its face. Luckily smog parts are warrantied for a while, so the dealer replaced it for free. It didn't set the check engine light on, which I thought was kind of weird. 

