The Green Lantern

Okay so I got a 04 gt with a bassani xpipe with high flow cats and a bassani cat back. I hear the noise mostley in 4th and 5th, sometimes in 3rd at low rpms, around 1500-2000. It sounds kind of like a ringing noise and seems to go away once up around 2300-2500. Sounds like its coming from the back of the car. Also i have the p0240 code coming up which is the cats messed up. i have o2 sensors in the car that i just put in, maybe a wire got burnt?

The Green Lantern

anybody?

turbo232

take a video while in the car so we can hear the ringing.