After reading about all the wastegate rattling on the 335i, I tested the 335i that I eventually bought, going to the dealer in the morning unannouced and tested the car.... no rattle...This morning, which is 4 days after collecting the car, I realized that upon startup from cold, my car does rattle for afew seconds then quieten down.The rattle is quite loud metal to metal sound, more like a heat shield rattling type of sound....I'm just wondering if it's the wastegate or something else ? Does the wastegate produce such a loud sound ? Or would it be more of a muted rattling ? Or does it mean wastegate going south big time ?? Any sure way of checking wastegate rattling ?