I have a 2001 GTP. Just rolled the 100k mark 3 weeks ago. Back in Aug my catalytic converter decided to eat itself away from the inside. Replaced it with a 3in DP with high flow cat from zzp. (check engine light wont go away still) The only other thing ive done besides that to the car is a drop in cone filter, autolite 104's, and replaced both o2 sensors.

I live in illinois and last month i had to pass emissions so i bought a o2 sim put it on cleared the code and havent seen it since. After the DP install should my CEL still be on?

Recently ive been having major driveability issues. Sometimes you give the car gas it goes how it should. Other times you give the car gas it falls straight on its face. It seems to happen in the higher RPMS.

When i bring the car to the dealership (it is under extended warranty, that didnt cover the cat) All they say is that i have a bad cat and thats the problem.

I checked the plugs they all look good. Havent gotten into the coils or anything else because i dont want to just throw money into parts and pray.

Any thought or comments or suggestions would be greatly appreciated.

here is a clip of my exhaust.... if you listen you can kind of hear a kind of thumb (sounds like a subwoofer on the otherside of the wall)