Thanks for the reply again. Yes, i ran my fingers all around the inside of the sub, including the port, and i didn't see or feel anything that was loose. The "rattle" comes from the bottom rear portion of the sub, and i made sure to check everything in that area. I'm starting to think now that i am trying to make the sub do something it can't duplicate very well, and my standards for it may be to high. Strange thing is, is that i don't think i run the sub that hot, as my system is properly calibrated. The Gain on the back of the sub is set to the middle position with the receivers gain set to -10. To me that doesn't seem like it's being pushed that hard, but maybe i could be wrong.