I had 6000 watts, 2000 RMS in the trunk with almost zero rattle. But then again I am very OCD sometimes. I stripped everything out of the whole car short of the dash. then I filled all of the cavities in, under, and around the car with expansion foam. There are a lot of them around the trunk. Then I removed the rubber flaps out of the vent in the bottom of the trunk, got rid of the spare tire and coated the entire floor from the dash to the trunk with sound deadening spray. I also put sound mat and four bolts in the license plate. Extra sound material over the sheet metal where the tail lights are took care ov the last few rattles. But like I said I'm OCD sometimes.
