Hey guys im new to the mustang world. i just bought my first 2000 ford mustang gt. So far I have a jlt intake, x pipes without cats, and flowmasters. My problem is that when i first bought the car with all the upgrades it did 160 miles before going on empty now ive noticed it did 210 miles before going on empty and also the check engine flashes? if you guys can help me out here that would be great 