Since you have an ATX....the car will do most of the work for you. You seem to be doing all the right things....by making your car lighter...but don't forget to try to have around 1/4 tank or so...this always helps.
Good Luck.
2000 WS6 Convertible A4 13.11 @ 107.5 with a lid, Ram Air and LTs
Gone:95 Mystique LS Young America edition V6, MTX 15.6 @ 91
