Let me know what you SA says because my SA can't think for himself.Mine is exactly that way since day one when she was new. Low RPM throttle in the bottom of 2nd, 3rd, 4th, you hear this distinct rattling sound and it goes away after the RPM starts to build. I am actually gonna bring this up to my SA on my next visit. Sounds like something is loose from the factory... I don't think it has anything to do with headers/ aftermarket exhausts... because mine was like that from day one.