My 1/4 dropped over 2 seconds with 4.10s and a Nelson tune. If you do most of your driving in town your mileage will usually go up unless you get on it like the guys above said. The throttle resonse is much better down low, but the only downside is your top speed is much lower and it takes a while to get from around 70-100 or above.

 

I have 4.10's and an A4.... I love my gear..... Definently a difference.... I agree that MPG was not affected by this choice.... I can cruise @75-80 on the highway and my RPM stays at or around 2500-2400

 

just put cam in there and you wont have to worry about top speed