[cochran]

Anyone know how to truly distinguish between a wastegate rattle vs exhaust flap rattle vs heatshield rattle? Currently on my 2009 e90 335 I'm getting a loud rattle on cold start for about 3 seconds, if i rev it in neutral I don't hear any rattle. However, on acceleration on low speeds ~0-40 mph i hear the rattle but as soon as i take my foot off the gas it immediately goes away. I've read a lot that wastegate rattle primarily rattles off deceleration, yet I only hear the rattle on acceleration and complete silence when foot is off gas. I just got downpipes put in recently so the rattle is significantly louder than it was before. Any input would be greatly appreciated!

Car is stock besides JB4 + VRSF downpipes (same rattle was heard although significantly quieter prior to DP's, and prior to JB4)

[limitdown]

I had a rattle on acceleration that turned out to be my midpipes hitting another part of the undercarriage. My Indy adjusted the mid and rear exhaust bolts and the rattling went away.