I finally got the old one off and the new one on. It made a world of difference in the way it sounds now. Made it overall louder and gave it a much deeper tone. The rumble at idle almost sounds like a 350. I'm guessing the old one was clogged pretty bad. The new one was a direct bolt on from autzone and it was about 3/4 of the size of the old one. Can i expect any increase in fuel mileage or anything like that? Is there anything else I should replace since I replaced the cat.