The looser you go on the converter, the worse your fuel mileage will be. I would though, if I were you, change to a 1,800-2,200 stall converter. It'll make the car more of a pleasure to drive on a daily basis and increase performance slightly because the converter will allow the motor to come "up on the cam" a little sooner than a stock converter. That's just my opinion. Others may see it a little differently.