If you dont have heat shields on any of your exhaust path ( check headers, up-pipe, turbo heaat shield up top, downpipe, midpipe, aaxleback ) you might have a physical rattle elsewhere. Exhaust hangers can sometime fail or rot out and put odd strain on connections and flanges making odd noises.
On a 10 year old car you may also have a bushing thats rotted out and the metal collar could be interacting with the bracket. I would check your drive line bushings from the pitch stop and engine mounts to the rear diff bushings. If its none of those there might be a body panel pin thats loose causing a rattle or noise.
I totally know where your coming from. i have a hatred for rattles and vibration noises. I dont mind feeling them but hearing metal rattling drives me up the walls. Ive gone so far as sliding neopreme shets under door cards and mating points between the dash and door cards to knock out squeaks and rattles.
Slow is Smooth > Smooth is Fast