hahaha! Where are you located at there buddy?

edit: alexandria....hmmm i dunno about that.
do you have any kind of lip on your car? My muffler kinda bumps up against my rear type r lip sometimes... If you have the stock exhaust check the heatshield on your muffler, my friends had rusted part of the way off and was rattling sometimes. Remove the heatshield for your header, cat.....you are missing a heatshield somewhere around your exhaust!! NOTHING else goes GRRRRRRSHT for 200rpms and then magically goes away. Shit, make sure your intake isn't bumping up against something. I dunno, perhaps a wheel is about to fall off.