Well.. a little update here. I was pulling out of the gas station last weekend and I got on it a little.. looked back and there was greyish smoke! I freaked out so I pulled in across the street into a parking lot.. gave it a few revs and the smoke went away.. so did the rattle. I found a some small chunks of something in the tail pipes. Seems the cat totally went away.
I sent an email to ShoShop about it and asked what their warranty is on their cat and y-pipe.
This totally sucks.. looks like I am going to have to put the stocker back on to get my car smogged.. cause I have a feeling this wont get settled anytime soon.
