My 99' 9-3 SE HOT makes a rattle when under hard acceleration. Especially when the turbo hits the red. I first thought it was the Cat, as the rattle sounds similar to a cat failure, but seems to be forward of the cat. Car does not make the noise under nomal acceleration. Could it be exhuast front of the cat like the manifold, turbo bearings, or what?? Any clues would be great...can't stomach another trip to the dealer.