2007 gt500 with 4800 miles. first start of the day in my garage i can hear a faint knock. its not loud and you couldnt hear it inside the car if i started it outside the garage. you can hear it if you get out the car though. i hear it from the bottom of the oil pan. no knock on top of the engine. completely stops once the needle starts to move on the temp gauge. i run the correct motor oil and oil filter also. car runs great and no other problems. anyone else hear this with their car???????

 

I had a strange knock in my 08 at one time...turns out the cats were falling apart and when warming up the ceramic was popping...the end result was a blast of white dust blowing out the exhaust at WOT...what caused this... the guy I bought the car from just put 558 miles on it idling around...unburned gas was getting into the cats and burning...causing much higher temps then the ceramic is made for...(a rich A/F mixture can cause this also)

 

bummer....get some headers and an H pipe you will be very happy with it