when i parked the car and turned it off and got out i noticed a fairly noticable clicking noise coming from under the car, ( sounded like metal clicking) but i could not tell if it was coming from under the enging or the catco...i noticed it because it was midnight and in pa you can hear someone sneeze a mile away..this is the first time i ever heard this noise... i will try to investagate in the day time when i can jack the carf up and see what im doing...

did it sound anything like the tick metal makes as it contracts during cooling? anywhere on your exhaust can make the sound which could be why it is hard to pin point if that is it.

Not trying to dismiss it as nothing, but if it were cool at midnight(thermally), then it could be from the thermal expansion as previously mentioned. It can sound like a "tick" or sometimes a "pang" so to speak. Let us know what you find.