So i just got this 03 GT and so far it's been good. However I just noticed a weird sound coming from the rear passenger side. It really only happens when I turn left (meaning the weight shifts to the right) and also i heard it a little going uphill. It kinda sounds like something is rubbing together, but it's not the tire. Anyone have any ideas??

 

Do you have an aftermarket cat-back on? Sometimes they rub on the inside of the tire.. Check the exhaust around the wheel well for rub marks.