rattle noise

[sd_boxster]

1) Loose heat shield. This is pretty common. Get it up in the air and poke around until you find the one that's rattling.
2) Catalytic converter is shot and you have chunks rattling around in your exhaust.

My money's on the heat shield...

[tuanle16]

i agree. that is exactly what it sounds like to me too. but again, i did get it up and banged around. could not locate it. i also knock around the cats and exhaust and pipes..no luck.

[jhandy]

if it is more of a clunky rattle, then look to the lower track arm (199$) often goes out, the plastic bushings go bad where it bolts to the frame. If it is a tinny rattle, then heat sheild. heat shield often make noise also with the car still and reving the motor.
driving about 10 mph over cobble stone road is the easiest way to hear the track arm.