So I've always noticed that when cold starting the Q it makes a fairly pronounced rattle/knock noise for the first 10-15 seconds then goes away. Anyone have any insight to what that is or have the same noise? I remember on the G37 similar cold start sounds but the Q's is soooo much more noticeable because after that initial 15 second window its absolutely gone and sounds wonderful. I've theorized that it's the timing chain but why would it make that rattling sound for 15 seconds then turn off like a switch. It's too clean of a stop in sound to be because of heat buildup, the cutoff sounds intentional almost.