I own a 1998 Mitsubishi Eclipse GS and had a Full Magnaflow Cat-Back Exhaust installed about half a year ago. About a month after it got installed I began hearing a light rattling noise coming from (what seems to be) under the center of car, I did notice that the pipe is up against the frame while it was parked. What could this be? Also, there seems to be a bit of smoke coming from the Catalytic Converter after driving it really hard. Thanks.