06 SL55 random metallic clicking noise
 

Sorry guys. Im new to this. Actually my first posting. I picked up 2006 SL55 AMG with 39k miles. Cars seems in great condition. Had it for about a month now. Completely in love after my 03 E320. Anyway, it makes this strange metallic clicking noise thats not very loud and i can only hear it when har ia hot and been running for a while. if you can picture the noise car makes when you shut it down after a hard run, its like that but only one click at a time. At low speeds. No bumps. No wheels turning. Completely randomly. Almost sounds like my catalytic is overheating and clicks here and there. I might be wrong. (I took out both resonators on both pipes) it was making the noise since I picked it up. Any takers on this issue?