My 03 WRX makes a very noticable thumping noise/feeling when I make a sharp turn, like when I'm going to park. It seems to be coming from the front wheels or suspension, but I can't be sure. I took it to a mechanic, and he said he couldn't see anything that was wrong with it, no blistering on the tires or anything. It tends to get worse the more I drive, so I figured it might be fluid related and changed out my transmission fluid and rear diff, but that didn't help at all. Any ideas?